diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/FuncEmitEventPropertiesBuilder.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/FuncEmitEventPropertiesBuilder.java
index 625b224af..6276f9e61 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/FuncEmitEventPropertiesBuilder.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/FuncEmitEventPropertiesBuilder.java
@@ -16,7 +16,6 @@
 package io.serverlessworkflow.fluent.func;
 
 import io.cloudevents.CloudEventData;
-import io.serverlessworkflow.api.reflection.func.SerializableFunction;
 import io.serverlessworkflow.api.types.func.ContextFunction;
 import io.serverlessworkflow.api.types.func.EventDataFunction;
 import io.serverlessworkflow.api.types.func.FilterFunction;
@@ -31,7 +30,7 @@ protected FuncEmitEventPropertiesBuilder self() {
     return this;
   }
 
-  public <T> FuncEmitEventPropertiesBuilder data(SerializableFunction<T, CloudEventData> function) {
+  public <T> FuncEmitEventPropertiesBuilder data(Function<T, CloudEventData> function) {
     this.eventProperties.setData(new EventDataFunction().withFunction(function));
     return this;
   }
diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/CommonFuncOps.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/CommonFuncOps.java
index 202813c7b..a3df01d5b 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/CommonFuncOps.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/CommonFuncOps.java
@@ -15,9 +15,6 @@
  */
 package io.serverlessworkflow.fluent.func.dsl;
 
-import io.serverlessworkflow.api.reflection.func.ReflectionUtils;
-import io.serverlessworkflow.api.reflection.func.SerializableFunction;
-import io.serverlessworkflow.api.reflection.func.SerializablePredicate;
 import io.serverlessworkflow.api.types.FlowDirectiveEnum;
 import io.serverlessworkflow.fluent.func.FuncCallTaskBuilder;
 import io.serverlessworkflow.fluent.func.FuncSwitchTaskBuilder;
@@ -32,9 +29,10 @@ default <T, V> Consumer<FuncCallTaskBuilder> fn(Function<T, V> function, Class<T
     return f -> f.function(function, argClass);
   }
 
-  default <T, V> Consumer<FuncCallTaskBuilder> fn(SerializableFunction<T, V> function) {
-    Class<T> clazz = ReflectionUtils.inferInputType(function);
-    return f -> f.function(function, clazz);
+  @SuppressWarnings("unchecked")
+  default <T, V> Consumer<FuncCallTaskBuilder> fn(Function<T, V> function, T... typeToken) {
+    Class<T> clazz = (Class<T>) typeToken.getClass().getComponentType();
+    return fn(function, clazz);
   }
 
   default Consumer<FuncSwitchTaskBuilder> cases(SwitchCaseConfigurer... cases) {
@@ -49,8 +47,9 @@ default <T> SwitchCaseSpec<T> caseOf(Predicate<T> when, Class<T> whenClass) {
     return new SwitchCaseSpec<T>().when(when, whenClass);
   }
 
-  default <T> SwitchCaseSpec<T> caseOf(SerializablePredicate<T> when) {
-    return new SwitchCaseSpec<T>().when(when, ReflectionUtils.inferInputType(when));
+  @SuppressWarnings("unchecked")
+  default <T> SwitchCaseSpec<T> caseOf(Predicate<T> when, T... typeToken) {
+    return caseOf(when, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   default SwitchCaseConfigurer caseDefault(String task) {
diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncCallStep.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncCallStep.java
index 036534b8a..07226c01c 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncCallStep.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncCallStep.java
@@ -31,6 +31,11 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
   private final Class<T> argClass;
   private final Class<R> returnClass;
 
+  @SuppressWarnings("unchecked")
+  private static <R> Class<R> defaultReturnClass(Class<R> c) {
+    return c != null ? c : (Class<R>) Object.class;
+  }
+
   /** Function<T,R> variant (unnamed). */
   FuncCallStep(Function<T, R> fn, Class<T> argClass, Class<R> returnClass) {
     this(null, fn, argClass, returnClass);
@@ -43,7 +48,7 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
     this.ctxFn = null;
     this.filterFn = null;
     this.argClass = argClass;
-    this.returnClass = returnClass;
+    this.returnClass = defaultReturnClass(returnClass);
   }
 
   /** ContextFunction<T,R> variant (unnamed). */
@@ -58,7 +63,7 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
     this.ctxFn = ctxFn;
     this.filterFn = null;
     this.argClass = argClass;
-    this.returnClass = returnClass;
+    this.returnClass = defaultReturnClass(returnClass);
   }
 
   /** FilterFunction<T,R> variant (unnamed). */
@@ -74,7 +79,7 @@ public final class FuncCallStep<T, R> extends Step<FuncCallStep<T, R>, FuncCallT
     this.ctxFn = null;
     this.filterFn = filterFn;
     this.argClass = argClass;
-    this.returnClass = returnClass;
+    this.returnClass = defaultReturnClass(returnClass);
   }
 
   @Override
diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncDSL.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncDSL.java
index 160d1b084..ca766e8ae 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncDSL.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncDSL.java
@@ -17,10 +17,6 @@
 
 import io.cloudevents.CloudEventData;
 import io.serverlessworkflow.api.reflection.func.InstanceIdFunction;
-import io.serverlessworkflow.api.reflection.func.ReflectionUtils;
-import io.serverlessworkflow.api.reflection.func.SerializableConsumer;
-import io.serverlessworkflow.api.reflection.func.SerializableFunction;
-import io.serverlessworkflow.api.reflection.func.SerializablePredicate;
 import io.serverlessworkflow.api.reflection.func.UniqueIdBiFunction;
 import io.serverlessworkflow.api.types.FlowDirectiveEnum;
 import io.serverlessworkflow.api.types.OAuth2AuthenticationData;
@@ -118,19 +114,18 @@ public static <T, V> Consumer<FuncCallTaskBuilder> fn(
    * @param <V> output type
    * @return a consumer that configures a {@code FuncCallTaskBuilder}
    */
-  public static <T, V> Consumer<FuncCallTaskBuilder> fn(SerializableFunction<T, V> function) {
-    return f ->
-        f.function(
-            function,
-            ReflectionUtils.inferInputType(function),
-            ReflectionUtils.inferResultType(function));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, V> Consumer<FuncCallTaskBuilder> fn(Function<T, V> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return OPS.fn(function, inputClass);
   }
 
   /**
    * Compose multiple switch cases into a single configurer for {@link FuncSwitchTaskBuilder}.
    *
-   * @param cases one or more {@link SwitchCaseConfigurer} built via {@link
-   *     #caseOf(SerializablePredicate)} or {@link #caseDefault(String)}
+   * @param cases one or more {@link SwitchCaseConfigurer} built via {@link #caseOf(Predicate,
+   *     Object[])} or {@link #caseDefault(String)}
    * @return a consumer to apply on a switch task builder
    */
   public static Consumer<FuncSwitchTaskBuilder> cases(SwitchCaseConfigurer... cases) {
@@ -156,8 +151,10 @@ public static <T> SwitchCaseSpec<T> caseOf(Predicate<T> when, Class<T> whenClass
    * @param <T> predicate input type
    * @return a fluent builder to set the consequent action (e.g., {@code then("taskName")})
    */
-  public static <T> SwitchCaseSpec<T> caseOf(SerializablePredicate<T> when) {
-    return OPS.caseOf(when);
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T> SwitchCaseSpec<T> caseOf(Predicate<T> when, T... typeToken) {
+    return OPS.caseOf(when, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -241,15 +238,17 @@ public static FuncListenSpec toAny(String... types) {
    * @param <T> input type to the function
    * @return a consumer to configure {@link FuncEmitTaskBuilder}
    */
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> Consumer<FuncEmitTaskBuilder> produced(
-      String type, SerializableFunction<T, CloudEventData> function) {
-    return event ->
-        event.event(e -> e.type(type).data(function, ReflectionUtils.inferInputType(function)));
+      String type, Function<T, CloudEventData> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return event -> event.event(e -> e.type(type).data(function, inputClass));
   }
 
   /**
-   * Same as {@link #produced(String, SerializableFunction)} but with an explicit input class to
-   * guide conversion.
+   * Same as {@link #produced(String, Function, Object[])} but with an explicit input class to guide
+   * conversion.
    *
    * @param type CloudEvent type
    * @param function function that maps workflow input to {@link CloudEventData}
@@ -262,16 +261,20 @@ public static <T> Consumer<FuncEmitTaskBuilder> produced(
     return event -> event.event(e -> e.type(type).data(function, inputClass));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> Consumer<FuncEmitTaskBuilder> produced(
-      String type, ContextFunction<T, CloudEventData> function) {
-    return event ->
-        event.event(e -> e.type(type).data(function, ReflectionUtils.inferInputType(function)));
+      String type, ContextFunction<T, CloudEventData> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return event -> event.event(e -> e.type(type).data(function, inputClass));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> Consumer<FuncEmitTaskBuilder> produced(
-      String type, FilterFunction<T, CloudEventData> function) {
-    return event ->
-        event.event(e -> e.type(type).data(function, ReflectionUtils.inferInputType(function)));
+      String type, FilterFunction<T, CloudEventData> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return event -> event.event(e -> e.type(type).data(function, inputClass));
   }
 
   /**
@@ -352,8 +355,10 @@ public static <T, R> FuncCallStep<T, R> withContext(ContextFunction<T, R> fn, Cl
     return withContext(null, fn, in);
   }
 
-  public static <T, R> FuncCallStep<T, R> withContext(ContextFunction<T, R> fn) {
-    return withContext(null, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withContext(ContextFunction<T, R> fn, T... typeToken) {
+    return withContext(null, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -368,7 +373,7 @@ public static <T, R> FuncCallStep<T, R> withContext(ContextFunction<T, R> fn) {
    */
   public static <T, R> FuncCallStep<T, R> withContext(
       String name, ContextFunction<T, R> fn, Class<T> in) {
-    return withContext(name, fn, in, ReflectionUtils.inferResultType(fn));
+    return withContext(name, fn, in, null);
   }
 
   public static <T, R> FuncCallStep<T, R> withContext(
@@ -376,8 +381,11 @@ public static <T, R> FuncCallStep<T, R> withContext(
     return new FuncCallStep<>(name, fn, in, out);
   }
 
-  public static <T, R> FuncCallStep<T, R> withContext(String name, ContextFunction<T, R> fn) {
-    return withContext(name, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withContext(
+      String name, ContextFunction<T, R> fn, T... typeToken) {
+    return withContext(name, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -409,7 +417,7 @@ public static <T, R> FuncCallStep<T, R> withFilter(FilterFunction<T, R> fn, Clas
    */
   public static <T, R> FuncCallStep<T, R> withFilter(
       String name, FilterFunction<T, R> fn, Class<T> in) {
-    return withFilter(name, fn, in, ReflectionUtils.inferResultType(fn));
+    return withFilter(name, fn, in, null);
   }
 
   public static <T, R> FuncCallStep<T, R> withFilter(
@@ -417,12 +425,17 @@ public static <T, R> FuncCallStep<T, R> withFilter(
     return new FuncCallStep<>(name, fn, in, out);
   }
 
-  public static <T, R> FuncCallStep<T, R> withFilter(FilterFunction<T, R> fn) {
-    return withFilter(null, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withFilter(FilterFunction<T, R> fn, T... typeToken) {
+    return withFilter(null, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
-  public static <T, R> FuncCallStep<T, R> withFilter(String name, FilterFunction<T, R> fn) {
-    return withFilter(name, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withFilter(
+      String name, FilterFunction<T, R> fn, T... typeToken) {
+    return withFilter(name, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -437,7 +450,7 @@ public static <T, R> FuncCallStep<T, R> withFilter(String name, FilterFunction<T
    */
   public static <T, R> FuncCallStep<T, R> withInstanceId(
       String name, InstanceIdFunction<T, R> fn, Class<T> in) {
-    return withInstanceId(name, fn, in, ReflectionUtils.inferResultType(fn));
+    return withInstanceId(name, fn, in, null);
   }
 
   public static <T, R> FuncCallStep<T, R> withInstanceId(
@@ -462,12 +475,18 @@ public static <T, R> FuncCallStep<T, R> withInstanceId(InstanceIdFunction<T, R>
     return withInstanceId(null, fn, in);
   }
 
-  public static <T, R> FuncCallStep<T, R> withInstanceId(String name, InstanceIdFunction<T, R> fn) {
-    return withInstanceId(name, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withInstanceId(
+      String name, InstanceIdFunction<T, R> fn, T... typeToken) {
+    return withInstanceId(name, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
-  public static <T, R> FuncCallStep<T, R> withInstanceId(InstanceIdFunction<T, R> fn) {
-    return withInstanceId(null, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withInstanceId(
+      InstanceIdFunction<T, R> fn, T... typeToken) {
+    return withInstanceId(null, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -516,13 +535,13 @@ static String defaultUniqueId(WorkflowContextData wctx, TaskContextData tctx) {
    * @param <R> result type
    * @return a named call step that can be chained with additional configurations
    * @see #withUniqueId(String, UniqueIdBiFunction, Class, Class)
-   * @see #withUniqueId(String, UniqueIdBiFunction)
+   * @see #withUniqueId(String, UniqueIdBiFunction, Object[])
    * @see #withUniqueId(UniqueIdBiFunction, Class)
-   * @see #withUniqueId(UniqueIdBiFunction)
+   * @see #withUniqueId(UniqueIdBiFunction, Object[])
    */
   public static <T, R> FuncCallStep<T, R> withUniqueId(
       String name, UniqueIdBiFunction<T, R> fn, Class<T> in) {
-    return withUniqueId(name, fn, in, ReflectionUtils.inferResultType(fn));
+    return withUniqueId(name, fn, in, null);
   }
 
   /**
@@ -561,9 +580,9 @@ public static <T, R> FuncCallStep<T, R> withUniqueId(
    * @param <R> result type
    * @return a named call step that can be chained with additional configurations
    * @see #withUniqueId(String, UniqueIdBiFunction, Class)
-   * @see #withUniqueId(String, UniqueIdBiFunction)
+   * @see #withUniqueId(String, UniqueIdBiFunction, Object[])
    * @see #withUniqueId(UniqueIdBiFunction, Class)
-   * @see #withUniqueId(UniqueIdBiFunction)
+   * @see #withUniqueId(UniqueIdBiFunction, Object[])
    */
   public static <T, R> FuncCallStep<T, R> withUniqueId(
       String name, UniqueIdBiFunction<T, R> fn, Class<T> in, Class<R> out) {
@@ -605,10 +624,13 @@ public static <T, R> FuncCallStep<T, R> withUniqueId(
    * @return a named call step that can be chained with additional configurations
    * @see #withUniqueId(String, UniqueIdBiFunction, Class)
    * @see #withUniqueId(String, UniqueIdBiFunction, Class, Class)
-   * @see #withUniqueId(UniqueIdBiFunction)
+   * @see #withUniqueId(UniqueIdBiFunction, Object[])
    */
-  public static <T, R> FuncCallStep<T, R> withUniqueId(String name, UniqueIdBiFunction<T, R> fn) {
-    return withUniqueId(name, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withUniqueId(
+      String name, UniqueIdBiFunction<T, R> fn, T... typeToken) {
+    return withUniqueId(name, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -644,7 +666,7 @@ public static <T, R> FuncCallStep<T, R> withUniqueId(String name, UniqueIdBiFunc
    * @return an unnamed call step that can be chained with additional configurations
    * @see #withUniqueId(String, UniqueIdBiFunction, Class)
    * @see #withUniqueId(String, UniqueIdBiFunction, Class, Class)
-   * @see #withUniqueId(UniqueIdBiFunction)
+   * @see #withUniqueId(UniqueIdBiFunction, Object[])
    */
   public static <T, R> FuncCallStep<T, R> withUniqueId(UniqueIdBiFunction<T, R> fn, Class<T> in) {
     return withUniqueId(null, fn, in);
@@ -678,12 +700,15 @@ public static <T, R> FuncCallStep<T, R> withUniqueId(UniqueIdBiFunction<T, R> fn
    * @param <T> input type (inferred automatically)
    * @param <R> result type (inferred automatically)
    * @return an unnamed call step that can be chained with additional configurations
-   * @see #withUniqueId(String, UniqueIdBiFunction)
+   * @see #withUniqueId(String, UniqueIdBiFunction, Object[])
    * @see #withUniqueId(UniqueIdBiFunction, Class)
    * @see #withUniqueId(String, UniqueIdBiFunction, Class)
    */
-  public static <T, R> FuncCallStep<T, R> withUniqueId(UniqueIdBiFunction<T, R> fn) {
-    return withUniqueId(null, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> withUniqueId(
+      UniqueIdBiFunction<T, R> fn, T... typeToken) {
+    return withUniqueId(null, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -699,8 +724,10 @@ public static <T> ConsumeStep<T> consume(Consumer<T> consumer, Class<T> inputCla
     return new ConsumeStep<>(consumer, inputClass);
   }
 
-  public static <T> ConsumeStep<T> consume(SerializableConsumer<T> consumer) {
-    return consume(consumer, ReflectionUtils.inferInputType(consumer));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T> ConsumeStep<T> consume(Consumer<T> consumer, T... typeToken) {
+    return consume(consumer, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -716,8 +743,10 @@ public static <T> ConsumeStep<T> consume(String name, Consumer<T> consumer, Clas
     return new ConsumeStep<>(name, consumer, inputClass);
   }
 
-  public static <T> ConsumeStep<T> consume(String name, SerializableConsumer<T> consumer) {
-    return consume(name, consumer, ReflectionUtils.inferInputType(consumer));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T> ConsumeStep<T> consume(String name, Consumer<T> consumer, T... typeToken) {
+    return consume(name, consumer, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -737,8 +766,10 @@ public static <T, R> FuncCallStep<T, R> agent(UniqueIdBiFunction<T, R> fn, Class
     return withUniqueId(fn, in);
   }
 
-  public static <T, R> FuncCallStep<T, R> agent(UniqueIdBiFunction<T, R> fn) {
-    return withUniqueId(fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> agent(UniqueIdBiFunction<T, R> fn, T... typeToken) {
+    return withUniqueId(fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -758,8 +789,11 @@ public static <T, R> FuncCallStep<T, R> agent(
     return withUniqueId(name, fn, in);
   }
 
-  public static <T, R> FuncCallStep<T, R> agent(String name, UniqueIdBiFunction<T, R> fn) {
-    return withUniqueId(name, fn, ReflectionUtils.inferInputType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> agent(
+      String name, UniqueIdBiFunction<T, R> fn, T... typeToken) {
+    return withUniqueId(name, fn, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -801,13 +835,15 @@ public static <T, R> FuncCallStep<T, R> function(
    * @param <R> output type
    * @return a call step
    */
-  public static <T, R> FuncCallStep<T, R> function(SerializableFunction<T, R> fn) {
-    return new FuncCallStep<>(
-        fn, ReflectionUtils.inferInputType(fn), ReflectionUtils.inferResultType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> function(Function<T, R> fn, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return new FuncCallStep<>(fn, inputClass, null);
   }
 
   /**
-   * Named variant of {@link #function(SerializableFunction)} with inferred input type.
+   * Named variant of {@link #function(Function, Object[])} with inferred input type.
    *
    * @param name task name
    * @param fn the function to execute
@@ -815,9 +851,11 @@ public static <T, R> FuncCallStep<T, R> function(SerializableFunction<T, R> fn)
    * @param <R> output type
    * @return a named call step
    */
-  public static <T, R> FuncCallStep<T, R> function(String name, SerializableFunction<T, R> fn) {
-    return new FuncCallStep<>(
-        name, fn, ReflectionUtils.inferInputType(fn), ReflectionUtils.inferResultType(fn));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public static <T, R> FuncCallStep<T, R> function(String name, Function<T, R> fn, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return new FuncCallStep<>(name, fn, inputClass, null);
   }
 
   /**
@@ -909,12 +947,12 @@ public static EmitStep emit(String name, Consumer<FuncEmitTaskBuilder> cfg) {
    * @param <T> input type
    * @return an {@link EmitStep}
    */
-  public static <T> EmitStep emit(String type, SerializableFunction<T, CloudEventData> fn) {
+  public static <T> EmitStep emit(String type, Function<T, CloudEventData> fn) {
     return new EmitStep(null, produced(type, fn));
   }
 
   /**
-   * Named variant of {@link #emit(String, SerializableFunction)}.
+   * Named variant of {@link #emit(String, Function)}.
    *
    * @param name task name
    * @param type CloudEvent type
@@ -922,8 +960,7 @@ public static <T> EmitStep emit(String type, SerializableFunction<T, CloudEventD
    * @param <T> input type
    * @return a named {@link EmitStep}
    */
-  public static <T> EmitStep emit(
-      String name, String type, SerializableFunction<T, CloudEventData> fn) {
+  public static <T> EmitStep emit(String name, String type, Function<T, CloudEventData> fn) {
     return new EmitStep(name, produced(type, fn));
   }
 
@@ -1004,7 +1041,7 @@ public static ListenStep listen(String name, FuncListenSpec spec) {
 
   /**
    * Low-level switch case configurer using a custom builder consumer. Prefer the {@link
-   * #caseOf(SerializablePredicate)} helpers when possible.
+   * #caseOf(Predicate, Object[])} helpers when possible.
    *
    * @param taskName optional task name
    * @param switchCase consumer to configure the {@link FuncSwitchTaskBuilder}
@@ -1026,8 +1063,8 @@ public static FuncTaskConfigurer switchCase(Consumer<FuncSwitchTaskBuilder> swit
   }
 
   /**
-   * Convenience to apply multiple {@link SwitchCaseConfigurer} built via {@link
-   * #caseOf(SerializablePredicate)}.
+   * Convenience to apply multiple {@link SwitchCaseConfigurer} built via {@link #caseOf(Predicate,
+   * Object[])}.
    *
    * @param cases case configurers
    * @return list configurer
@@ -1382,9 +1419,12 @@ public static <T> FuncTaskConfigurer switchWhenOrElse(
     return switchWhenOrElse(null, pred, thenTask, otherwise, predClass);
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> FuncTaskConfigurer switchWhenOrElse(
-      SerializablePredicate<T> pred, String thenTask, FlowDirectiveEnum otherwise) {
-    return switchWhenOrElse(null, pred, thenTask, otherwise);
+      Predicate<T> pred, String thenTask, FlowDirectiveEnum otherwise, T... typeToken) {
+    return switchWhenOrElse(
+        null, pred, thenTask, otherwise, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -1410,13 +1450,16 @@ public static <T> FuncTaskConfigurer switchWhenOrElse(
             FuncDSL.cases(caseOf(pred, predClass).then(thenTask), caseDefault(otherwise)));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> FuncTaskConfigurer switchWhenOrElse(
       String taskName,
-      SerializablePredicate<T> pred,
+      Predicate<T> pred,
       String thenTask,
-      FlowDirectiveEnum otherwise) {
+      FlowDirectiveEnum otherwise,
+      T... typeToken) {
     return switchWhenOrElse(
-        taskName, pred, thenTask, otherwise, ReflectionUtils.inferInputType(pred));
+        taskName, pred, thenTask, otherwise, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -1434,9 +1477,12 @@ public static <T> FuncTaskConfigurer switchWhenOrElse(
     return switchWhenOrElse(null, pred, thenTask, otherwiseTask, predClass);
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> FuncTaskConfigurer switchWhenOrElse(
-      SerializablePredicate<T> pred, String thenTask, String otherwiseTask) {
-    return switchWhenOrElse(null, pred, thenTask, otherwiseTask);
+      Predicate<T> pred, String thenTask, String otherwiseTask, T... typeToken) {
+    return switchWhenOrElse(
+        null, pred, thenTask, otherwiseTask, (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -1461,10 +1507,16 @@ public static <T> FuncTaskConfigurer switchWhenOrElse(
             taskName, cases(caseOf(pred, predClass).then(thenTask), caseDefault(otherwiseTask)));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T> FuncTaskConfigurer switchWhenOrElse(
-      String taskName, SerializablePredicate<T> pred, String thenTask, String otherwiseTask) {
+      String taskName, Predicate<T> pred, String thenTask, String otherwiseTask, T... typeToken) {
     return switchWhenOrElse(
-        taskName, pred, thenTask, otherwiseTask, ReflectionUtils.inferInputType(pred));
+        taskName,
+        pred,
+        thenTask,
+        otherwiseTask,
+        (Class<T>) typeToken.getClass().getComponentType());
   }
 
   /**
@@ -1558,13 +1610,18 @@ public static FuncTaskConfigurer switchWhenOrElse(
    * @param <T> input type for the collection function
    * @return list configurer
    */
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T, V> FuncTaskConfigurer forEach(
-      SerializableFunction<T, Collection<V>> collection, Consumer<FuncTaskItemListBuilder> body) {
-    return forEach(null, collection, body);
+      Function<T, Collection<V>> collection,
+      Consumer<FuncTaskItemListBuilder> body,
+      T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return list -> list.forEach(null, j -> j.collection(collection, inputClass).tasks(body));
   }
 
   /**
-   * Named variant of {@link #forEach(SerializableFunction, Consumer)}.
+   * Named variant of {@link #forEach(Function, Consumer, Object[])}.
    *
    * @param taskName task name for the for-loop task
    * @param collection function that returns the collection to iterate
@@ -1572,41 +1629,59 @@ public static <T, V> FuncTaskConfigurer forEach(
    * @param <T> input type for the collection function
    * @return list configurer
    */
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T, V> FuncTaskConfigurer forEach(
       String taskName,
-      SerializableFunction<T, Collection<V>> collection,
-      Consumer<FuncTaskItemListBuilder> body) {
-    return list ->
-        list.forEach(
-            taskName,
-            j -> j.collection(collection, ReflectionUtils.inferInputType(collection)).tasks(body));
+      Function<T, Collection<V>> collection,
+      Consumer<FuncTaskItemListBuilder> body,
+      T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return list -> list.forEach(taskName, j -> j.collection(collection, inputClass).tasks(body));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T, V> FuncTaskConfigurer forEach(
-      SerializableFunction<T, Collection<V>> collection, LoopFunction<T, V, ?> function) {
-    return forEach(null, collection, function);
+      Function<T, Collection<V>> collection, LoopFunction<T, V, ?> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return list -> list.forEach(null, j -> j.collection(collection, inputClass).tasks(function));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T, V> FuncTaskConfigurer forEach(
       String taskName,
-      SerializableFunction<T, Collection<V>> collection,
-      LoopFunction<T, V, ?> function) {
+      Function<T, Collection<V>> collection,
+      LoopFunction<T, V, ?> function,
+      T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
     return list ->
-        list.forEach(
-            taskName,
-            j ->
-                j.collection(collection, ReflectionUtils.inferInputType(collection))
-                    .tasks(function));
+        list.forEach(taskName, j -> j.collection(collection, inputClass).tasks(function));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T, V> FuncTaskConfigurer forEachItem(
-      SerializableFunction<T, Collection<V>> collection, Function<V, ?> function) {
-    return forEachItem(null, collection, function);
+      Function<T, Collection<V>> collection, Function<V, ?> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return list ->
+        list.forEach(
+            null, j -> j.collection(collection, inputClass).tasks((t, v) -> function.apply((V) v)));
   }
 
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
   public static <T, V> FuncTaskConfigurer forEachItem(
-      String taskName, SerializableFunction<T, Collection<V>> collection, Function<V, ?> function) {
-    return forEach(taskName, collection, ((t, v) -> function.apply((V) v)));
+      String taskName,
+      Function<T, Collection<V>> collection,
+      Function<V, ?> function,
+      T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    return list ->
+        list.forEach(
+            taskName,
+            j -> j.collection(collection, inputClass).tasks((t, v) -> function.apply((V) v)));
   }
 
   /**
diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEmitSpec.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEmitSpec.java
index 7b7f9beec..48ab8dd74 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEmitSpec.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEmitSpec.java
@@ -18,8 +18,6 @@
 import io.cloudevents.CloudEventData;
 import io.cloudevents.core.data.BytesCloudEventData;
 import io.cloudevents.core.data.PojoCloudEventData;
-import io.serverlessworkflow.api.reflection.func.ReflectionUtils;
-import io.serverlessworkflow.api.reflection.func.SerializableFunction;
 import io.serverlessworkflow.api.types.func.ContextFunction;
 import io.serverlessworkflow.api.types.func.EventDataFunction;
 import io.serverlessworkflow.fluent.func.FuncEmitEventPropertiesBuilder;
@@ -40,8 +38,10 @@ protected FuncEmitSpec self() {
   }
 
   /** Sets the event data and the contentType to `application/json` */
-  public <T> FuncEmitSpec jsonData(SerializableFunction<T, CloudEventData> function) {
-    Class<T> clazz = ReflectionUtils.inferInputType(function);
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T> FuncEmitSpec jsonData(Function<T, CloudEventData> function, T... typeToken) {
+    Class<T> clazz = (Class<T>) typeToken.getClass().getComponentType();
     addPropertyStep(e -> e.data(new EventDataFunction().withFunction(function, clazz)));
     return JSON();
   }
diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEventFilterSpec.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEventFilterSpec.java
index 3b8c08236..963cc259e 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEventFilterSpec.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEventFilterSpec.java
@@ -21,7 +21,6 @@
 import io.cloudevents.core.CloudEventUtils;
 import io.cloudevents.core.data.PojoCloudEventData;
 import io.cloudevents.jackson.PojoCloudEventDataMapper;
-import io.serverlessworkflow.api.reflection.func.SerializablePredicate;
 import io.serverlessworkflow.api.types.func.ContextPredicate;
 import io.serverlessworkflow.api.types.func.FilterPredicate;
 import io.serverlessworkflow.fluent.func.FuncEventFilterBuilder;
@@ -32,6 +31,7 @@
 import io.serverlessworkflow.impl.jackson.JsonUtils;
 import java.util.Map;
 import java.util.Objects;
+import java.util.function.Predicate;
 
 /**
  * Fluent DSL specification builder for configuring CloudEvent filters within a Serverless Workflow
@@ -58,7 +58,7 @@ protected FuncEventFilterSpec self() {
    * @param predicate the predicate to evaluate against the entire {@link CloudEvent}.
    * @return the current {@link FuncEventFilterSpec} instance.
    */
-  public FuncEventFilterSpec envelope(SerializablePredicate<CloudEvent> predicate) {
+  public FuncEventFilterSpec envelope(Predicate<CloudEvent> predicate) {
     addPropertyStep(e -> e.envelope(predicate));
     return this;
   }
@@ -95,7 +95,7 @@ public FuncEventFilterSpec envelope(FilterPredicate<CloudEvent> predicate) {
    * @param predicate the predicate to evaluate against the event data.
    * @return the current {@link FuncEventFilterSpec} instance.
    */
-  public FuncEventFilterSpec data(SerializablePredicate<CloudEventData> predicate) {
+  public FuncEventFilterSpec data(Predicate<CloudEventData> predicate) {
     addPropertyStep(e -> e.data(predicate));
     return this;
   }
@@ -139,7 +139,7 @@ public FuncEventFilterSpec data(FilterPredicate<CloudEventData> predicate) {
    * @param predicate the predicate to evaluate against the parsed Map.
    * @return the current {@link FuncEventFilterSpec} instance.
    */
-  public FuncEventFilterSpec dataAsMap(SerializablePredicate<Map<String, Object>> predicate) {
+  public FuncEventFilterSpec dataAsMap(Predicate<Map<String, Object>> predicate) {
     addPropertyStep(
         e ->
             e.envelope(
@@ -202,7 +202,7 @@ public FuncEventFilterSpec dataAsMap(FilterPredicate<Map<String, Object>> predic
    * @param <T> The target type.
    * @return the current {@link FuncEventFilterSpec} instance.
    */
-  public <T> FuncEventFilterSpec dataAs(Class<T> targetType, SerializablePredicate<T> predicate) {
+  public <T> FuncEventFilterSpec dataAs(Class<T> targetType, Predicate<T> predicate) {
     addPropertyStep(
         e ->
             e.envelope(
diff --git a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/Step.java b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/Step.java
index 2f5055b09..0ce509c32 100644
--- a/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/Step.java
+++ b/experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/Step.java
@@ -15,9 +15,6 @@
  */
 package io.serverlessworkflow.fluent.func.dsl;
 
-import io.serverlessworkflow.api.reflection.func.ReflectionUtils;
-import io.serverlessworkflow.api.reflection.func.SerializableFunction;
-import io.serverlessworkflow.api.reflection.func.SerializablePredicate;
 import io.serverlessworkflow.api.types.FlowDirectiveEnum;
 import io.serverlessworkflow.api.types.func.ContextFunction;
 import io.serverlessworkflow.api.types.func.FilterFunction;
@@ -51,11 +48,11 @@ protected SELF self() {
   // ---------------------------------------------------------------------------
 
   /** Queue a {@code when(predicate)} to be applied on the concrete builder. */
-  public <T> SELF when(SerializablePredicate<T> predicate) {
-    postConfigurers.add(
-        b ->
-            ((ConditionalTaskBuilder<?>) b)
-                .when(predicate, ReflectionUtils.inferInputType(predicate)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T> SELF when(Predicate<T> predicate, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((ConditionalTaskBuilder<?>) b).when(predicate, inputClass));
     return self();
   }
 
@@ -127,11 +124,11 @@ public SELF then(FlowDirectiveEnum directive) {
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTaskTransformations#exportAs(Function)
    */
-  public <T, R> SELF exportAs(SerializableFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .exportAs(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF exportAs(Function<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).exportAs(function, inputClass));
     return self();
   }
 
@@ -165,11 +162,11 @@ public <T, R> SELF exportAs(Function<T, R> function, Class<T> taskResultClass) {
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTaskTransformations#exportAs(FilterFunction)
    */
-  public <T, R> SELF exportAs(FilterFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .exportAs(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF exportAs(FilterFunction<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).exportAs(function, inputClass));
     return self();
   }
 
@@ -202,11 +199,11 @@ public <T, R> SELF exportAs(FilterFunction<T, R> function, Class<T> taskResultCl
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTaskTransformations#exportAs(ContextFunction)
    */
-  public <T, R> SELF exportAs(ContextFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .exportAs(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF exportAs(ContextFunction<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).exportAs(function, inputClass));
     return self();
   }
 
@@ -288,11 +285,11 @@ public SELF exportAs(String jqExpression) {
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTransformations#outputAs(Function)
    */
-  public <T, R> SELF outputAs(SerializableFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .outputAs(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF outputAs(Function<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).outputAs(function, inputClass));
     return self();
   }
 
@@ -344,11 +341,11 @@ public <T, R> SELF outputAs(Function<T, R> function, Class<T> taskResultClass) {
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTransformations#outputAs(FilterFunction)
    */
-  public <T, R> SELF outputAs(FilterFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .outputAs(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF outputAs(FilterFunction<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).outputAs(function, inputClass));
     return self();
   }
 
@@ -380,11 +377,11 @@ public <T, R> SELF outputAs(FilterFunction<T, R> function, Class<T> taskResultCl
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTransformations#outputAs(ContextFunction)
    */
-  public <T, R> SELF outputAs(ContextFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .outputAs(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF outputAs(ContextFunction<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).outputAs(function, inputClass));
     return self();
   }
 
@@ -450,11 +447,11 @@ public SELF outputAs(String jqExpression) {
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTransformations#inputFrom(Function)
    */
-  public <T, R> SELF inputFrom(SerializableFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .inputFrom(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF inputFrom(Function<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).inputFrom(function, inputClass));
     return self();
   }
 
@@ -509,11 +506,11 @@ public <T, R> SELF inputFrom(Function<T, R> function, Class<T> inputClass) {
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTransformations#inputFrom(FilterFunction)
    */
-  public <T, R> SELF inputFrom(FilterFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .inputFrom(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF inputFrom(FilterFunction<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).inputFrom(function, inputClass));
     return self();
   }
 
@@ -547,11 +544,11 @@ public <T, R> SELF inputFrom(FilterFunction<T, R> function, Class<T> inputClass)
    * @return this step for method chaining
    * @see io.serverlessworkflow.fluent.func.spi.FuncTransformations#inputFrom(ContextFunction)
    */
-  public <T, R> SELF inputFrom(ContextFunction<T, R> function) {
-    postConfigurers.add(
-        b ->
-            ((FuncTaskTransformations<?>) b)
-                .inputFrom(function, ReflectionUtils.inferInputType(function)));
+  @SafeVarargs
+  @SuppressWarnings("unchecked")
+  public final <T, R> SELF inputFrom(ContextFunction<T, R> function, T... typeToken) {
+    Class<T> inputClass = (Class<T>) typeToken.getClass().getComponentType();
+    postConfigurers.add(b -> ((FuncTaskTransformations<?>) b).inputFrom(function, inputClass));
     return self();
   }
 
diff --git a/experimental/fluent/func/src/test/java/io/serverlessworkflow/fluent/func/FuncDSLTest.java b/experimental/fluent/func/src/test/java/io/serverlessworkflow/fluent/func/FuncDSLTest.java
index 1f518e99c..def4f2595 100644
--- a/experimental/fluent/func/src/test/java/io/serverlessworkflow/fluent/func/FuncDSLTest.java
+++ b/experimental/fluent/func/src/test/java/io/serverlessworkflow/fluent/func/FuncDSLTest.java
@@ -668,4 +668,24 @@ void grpc_unnamed_call_builds_task() {
     assertInstanceOf(CallGRPC.class, t.getCallTask().get());
     assertEquals("Call", ((CallGRPC) t.getCallTask().get()).getWith().getMethod());
   }
+
+  @Test
+  @DisplayName(
+      "function with nested generic Map<String, List<Integer>> preserves type safety in lambda")
+  void function_with_nested_generics_preserves_type_safety() {
+    Workflow wf =
+        FuncWorkflowBuilder.workflow("nested-generics")
+            .tasks(
+                function(
+                    (Map<String, List<Integer>> map) -> {
+                      List<Integer> values = map.get("scores");
+                      int total = values.stream().mapToInt(Integer::intValue).sum();
+                      return Map.of("total", total, "count", values.size());
+                    }))
+            .build();
+
+    List<TaskItem> items = wf.getDo();
+    assertEquals(1, items.size());
+    assertNotNull(items.get(0).getTask().getCallTask(), "CallTask expected");
+  }
 }
diff --git a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/InstanceIdFunction.java b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/InstanceIdFunction.java
index 083456d4f..25efee030 100644
--- a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/InstanceIdFunction.java
+++ b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/InstanceIdFunction.java
@@ -15,8 +15,6 @@
  */
 package io.serverlessworkflow.api.reflection.func;
 
-import java.io.Serializable;
-
 /**
  * Functions that expect a workflow instance ID injection in runtime
  *
@@ -24,6 +22,6 @@
  * @param <R> The task result output
  */
 @FunctionalInterface
-public interface InstanceIdFunction<T, R> extends Serializable {
+public interface InstanceIdFunction<T, R> {
   R apply(String instanceId, T payload);
 }
diff --git a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/ReflectionUtils.java b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/ReflectionUtils.java
deleted file mode 100644
index 6b30fcdb2..000000000
--- a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/ReflectionUtils.java
+++ /dev/null
@@ -1,101 +0,0 @@
-/*
- * Copyright 2020-Present The Serverless Workflow Specification Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package io.serverlessworkflow.api.reflection.func;
-
-import io.serverlessworkflow.api.types.func.ContextFunction;
-import io.serverlessworkflow.api.types.func.FilterFunction;
-import java.lang.invoke.MethodType;
-import java.lang.invoke.SerializedLambda;
-import java.lang.reflect.Method;
-import java.util.function.Function;
-
-/**
- * Specially used by {@link Function} parameters in the Java Function.
- *
- * @see <a href="https://www.baeldung.com/java-serialize-lambda">Serialize a Lambda in Java</a>
- */
-public final class ReflectionUtils {
-
-  private ReflectionUtils() {}
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(ContextFunction<T, ?> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 0);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(FilterFunction<T, ?> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 0);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(SerializableFunction<T, ?> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 0);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(SerializablePredicate<T> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 0);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(InstanceIdFunction<T, ?> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 1);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(UniqueIdBiFunction<T, ?> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 1);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferInputType(SerializableConsumer<T> fn) {
-    return (Class<T>) inferInputTypeFromAny(fn, 0);
-  }
-
-  @SuppressWarnings("unchecked")
-  public static <T> Class<T> inferResultType(Object fn) {
-    return (Class<T>) inferMethodType(fn).returnType();
-  }
-
-  /**
-   * Extracts the input type using the resolved interface signature. * @param fn The serializable
-   * lambda
-   *
-   * @param lambdaParamIndex The index of the payload parameter in the interface's apply method
-   */
-  public static Class<?> inferInputTypeFromAny(Object fn, int lambdaParamIndex) {
-    return inferMethodType(fn).parameterArray()[lambdaParamIndex];
-  }
-
-  private static MethodType inferMethodType(Object fn) {
-    try {
-      Method m = fn.getClass().getDeclaredMethod("writeReplace");
-      m.setAccessible(true);
-      SerializedLambda sl = (SerializedLambda) m.invoke(fn);
-
-      ClassLoader cl = fn.getClass().getClassLoader();
-
-      // getInstantiatedMethodType() provides the exact generic signature resolved
-      // by the compiler, completely bypassing captured variables and method kind switches!
-
-      return MethodType.fromMethodDescriptorString(sl.getInstantiatedMethodType(), cl);
-    } catch (ReflectiveOperationException ex) {
-      throw new IllegalStateException(
-          "Cannot infer type from lambda. Pass Class<T> or use a method reference.", ex);
-    }
-  }
-}
diff --git a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableConsumer.java b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableConsumer.java
deleted file mode 100644
index 60df61d0c..000000000
--- a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableConsumer.java
+++ /dev/null
@@ -1,22 +0,0 @@
-/*
- * Copyright 2020-Present The Serverless Workflow Specification Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package io.serverlessworkflow.api.reflection.func;
-
-import java.io.Serializable;
-import java.util.function.Consumer;
-
-@FunctionalInterface
-public interface SerializableConsumer<T> extends Consumer<T>, Serializable {}
diff --git a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableFunction.java b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableFunction.java
deleted file mode 100644
index c4b2eee08..000000000
--- a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableFunction.java
+++ /dev/null
@@ -1,29 +0,0 @@
-/*
- * Copyright 2020-Present The Serverless Workflow Specification Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package io.serverlessworkflow.api.reflection.func;
-
-import java.io.Serializable;
-import java.util.function.Function;
-
-/**
- * Alternative to Function for our DSL to discover the input parameter class in runtime via
- * reflection.
- *
- * @param <T>
- * @param <R>
- */
-@FunctionalInterface
-public interface SerializableFunction<T, R> extends Function<T, R>, Serializable {}
diff --git a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializablePredicate.java b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializablePredicate.java
deleted file mode 100644
index a960b8db8..000000000
--- a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializablePredicate.java
+++ /dev/null
@@ -1,22 +0,0 @@
-/*
- * Copyright 2020-Present The Serverless Workflow Specification Authors
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package io.serverlessworkflow.api.reflection.func;
-
-import java.io.Serializable;
-import java.util.function.Predicate;
-
-@FunctionalInterface
-public interface SerializablePredicate<T> extends Predicate<T>, Serializable {}
diff --git a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/UniqueIdBiFunction.java b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/UniqueIdBiFunction.java
index 4340cc3f8..4e1378c69 100644
--- a/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/UniqueIdBiFunction.java
+++ b/experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/UniqueIdBiFunction.java
@@ -15,7 +15,6 @@
  */
 package io.serverlessworkflow.api.reflection.func;
 
-import java.io.Serializable;
 import java.util.function.BiFunction;
 
 /**
@@ -26,6 +25,6 @@
  * @param <R> The task result output
  */
 @FunctionalInterface
-public interface UniqueIdBiFunction<T, R> extends BiFunction<String, T, R>, Serializable {
+public interface UniqueIdBiFunction<T, R> extends BiFunction<String, T, R> {
   R apply(String uniqueId, T object);
 }