Worked on the langchain4j/langchain4j repository, focusing on improving the AwsDocumentConverter by addressing a bug related to required parameter validation. Refactored the logic to ensure only explicitly listed properties are marked as required, resolving an issue that previously caused all parameters to be treated as mandatory. Developed comprehensive unit tests in Java using JUnit to cover scenarios with empty properties and null parameters, ensuring robust validation. Verified the fix across both core and main modules, confirming stability and reliability. Maintained strong pull request hygiene by grouping tests, validation, and non-breaking changes into a single, coherent update to the codebase.