Improve exception handling for missing converters

[andreas-grafenberger]

Motivation and Context

The Enhanced Client currently fails to build converters for collection fields such as Map<String, Object>, Set<Object>, and List<Object> with an unhelpful Index: 0 exception.

This occurs because DefaultAttributeConverterProvider.findConverterInternal(EnhancedType<T> type) checks collection assignability in the wrong direction. As a result, broad types such as Object.class can be incorrectly treated as Map, Set, or List types, even though they do not provide the required generic type parameters.

This PR corrects these checks so unsupported collection types fail with a meaningful converter-not-found error instead of exposing an internal generic-type-list implementation detail.

See also:

Reference	Customer need	Status
Issue #1902	Support arbitrary and searchable Map<String, Object> values	Closed feature request
Issue #2296	Correct the reversed type check that treats Object as a map	Open bug, P2
Issue #3845	Replace the internal exception with a clear converter-not-found error	Open feature request, P2
PR #5538	Validate converter input and improve the error	Open and unmerged

Modifications

• Updated the collection type checks in DefaultAttributeConverterProvider.findConverterInternal(EnhancedType<T> type) to use exact type matching.

  Previous behavior:

  if (type.rawClass().isAssignableFrom(Map.class)) {
  } else if (type.rawClass().isAssignableFrom(Set.class)) {
  } else if (type.rawClass().isAssignableFrom(List.class)) {
  }

  New behavior:

  if (Map.class.equals(type.rawClass())) {
  } else if (Set.class.equals(type.rawClass())) {
  } else if (List.class.equals(type.rawClass())) {
  }

• Prevented Object.class and other broad types from being incorrectly interpreted as Map, Set, or List types.

• Changed failures for unsupported collection types such as Map<String, Object>, Set<Object>, and List<Object> from the internal Index: 0 error to a meaningful converter-not-found error, for example:

  IllegalStateException: Converter not found for EnhancedType(Map<String, Object>)
  

• Applications that require support for these types can continue to register custom AttributeConverter implementations.

Testing

Test Coverage on modified classes

TBC

Test Coverage Checklist

TBC

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

Checklist

• I have read the CONTRIBUTING document
• Local run of mvn install succeeds
• My code follows the code style of this project
• My change requires a change to the Javadoc documentation
• I have updated the Javadoc documentation accordingly
• I have added tests to cover my changes
• All new and existing tests passed
• I have added a changelog entry. Adding a new entry must be accomplished by running the scripts/new-change script and following the instructions. Commit the new file created by the script in .changes/next-release with your changes.
• My change is to implement 1.11 parity feature and I have updated LaunchChangelog

License

• I confirm that this pull request can be released under the Apache 2 license