Replace serialization-based type inference with reified varargs type token

[mdproctor]

Summary

• Replace SerializableFunction/SerializablePredicate/SerializableConsumer + ReflectionUtils.inferInputType() with the reified varargs type token pattern across ~40 call sites
• Delete ReflectionUtils, SerializableFunction, SerializablePredicate, SerializableConsumer — no longer needed
• Drop Serializable from InstanceIdFunction and UniqueIdBiFunction (was only needed for the inference hack)
• Add test demonstrating nested generic type safety (Map<String, List<Integer>>)

Motivation

The previous approach used JVM serialization internals (writeReplace → SerializedLambda → getInstantiatedMethodType) to recover erased type parameters at runtime. This is:

• Fragile — depends on undocumented JVM serialization behavior
• Restrictive — forces all lambdas to implement Serializable
• Heavyweight — serialization roundtrip + reflection per inference call

The reified varargs type token pattern achieves the same result (recovering the raw Class<T> at runtime) with zero reflection, zero serialization, and works with any lambda or method reference regardless of serializability. Java reifies array creation at the call site even for generic varargs parameters, so T... typeToken with zero arguments creates a new T[0] whose component type is recoverable via getClass().getComponentType().

Test plan

• All existing tests pass (0 regressions)
• New test: function_with_nested_generics_preserves_type_safety — verifies Map<String, List<Integer>> flows through with compile-time type safety
• IntelliJ build: 0 errors

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR removes the previous serialization/SerializedLambda-based runtime type inference utilities and migrates the fluent function DSL to a “reified varargs type token” approach for recovering the raw input Class<T> at call sites, eliminating the need for Serializable* functional interfaces and ReflectionUtils.

Changes:

• Deleted ReflectionUtils and the SerializableFunction/SerializablePredicate/SerializableConsumer helper interfaces; removed Serializable from InstanceIdFunction and UniqueIdBiFunction.
• Updated fluent DSL entrypoints (FuncDSL, Step, CommonFuncOps, and related specs/builders) to accept standard JDK functional interfaces plus an optional varargs type token for input class inference.
• Added a test intended to demonstrate nested generic lambda type safety.

Reviewed changes

Copilot reviewed 13 out of 13 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/UniqueIdBiFunction.java	Drops Serializable from the functional interface now that serialization inference is removed.
experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializablePredicate.java	Removed obsolete serializable predicate shim.
experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableFunction.java	Removed obsolete serializable function shim.
experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/SerializableConsumer.java	Removed obsolete serializable consumer shim.
experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/ReflectionUtils.java	Deleted serialization/reflection-based lambda type inference utility.
experimental/types/src/main/java/io/serverlessworkflow/api/reflection/func/InstanceIdFunction.java	Drops Serializable from the functional interface now that serialization inference is removed.
experimental/fluent/func/src/test/java/io/serverlessworkflow/fluent/func/FuncDSLTest.java	Adds a nested-generics-focused test for the updated DSL typing behavior.
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/FuncEmitEventPropertiesBuilder.java	Accepts Function directly instead of a serializable wrapper.
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/Step.java	Replaces reflection-based inference with varargs type token input-class derivation for chained operations.
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEventFilterSpec.java	Switches envelope/data filter overloads from serializable predicates to standard Predicate.
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncEmitSpec.java	Adds varargs type-token overload for JSON event data emission.
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/FuncDSL.java	Updates core DSL helpers to use varargs type tokens for input class inference and removes reflection-based return-type inference wiring.
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/CommonFuncOps.java	Updates shared DSL ops to accept standard Function/Predicate with type-token inference.

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