Summary

This PR improves Spring MVC request parameter binding for primitive boolean
types in two edge cases:

1. Invalid boolean values for @RequestParam boolean now consistently
   result in MethodArgumentTypeMismatchException, leading to HTTP 400.
2. Missing primitive boolean parameters declared with
   @RequestParam(required = false) now default to false instead of
   raising a type mismatch exception.

Motivation

Previously:

• Invalid boolean values could fail inconsistently.
• Primitive boolean parameters with required=false would still raise
  TypeMismatchException when missing, despite being optional.

This behavior was surprising and inconsistent with developer expectations.

Changes

• Updated AbstractNamedValueMethodArgumentResolver to correctly handle
  missing primitive boolean parameters when required=false.
• Ensured invalid boolean values fail fast with a consistent exception.
• Added regression tests in RequestMappingHandlerAdapterTests.

Impact

• Backward-compatible
• Improves correctness and developer experience
• No public API changes