Version 6.7.0 release

[RamukaRitik]

Changed

• Added support for version v2.1-25.4.01.00 of the DocuSign ESignature API.
• Updated the SDK release version.

Security

• Enforced TLS certificate validation and hostname verification by default using the system's default trust store. Previously, all certificates were trusted without validation.
• Enforced HTTPS-only base paths. setBasePath() and setOAuthBasePath() now reject http:// URLs. Use ApiClient.insecure() for local testing with HTTP or self-signed certificates.
• Scoped proxy credentials to the configured proxy host and port. Added setPerConnectionProxyAuth(true) to opt in to per-connection proxy authentication, avoiding JVM-wide side effects.

Breaking Changes

• ApiClient(String basePath) and setBasePath(String) throw IllegalArgumentException for http:// URLs. Migrate to ApiClient.insecure(basePath).
• Removed constructor overloads accepting boolean perConnectionProxyAuth. Use the standard constructor followed by .setPerConnectionProxyAuth(true).