feat: Enhance LangChain4j with MCP tool handling

[curefat]

This update introduces support for MCP tools with parametersJsonSchema in LangChain4j, enhancing the tool specification handling. Additionally, code readability is improved by refactoring several sections for clarity and consistency.

[gemini-code-assist]

Summary of Changes

Hello @curefat, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request significantly enhances LangChain4j's capabilities by integrating support for MCP tools that utilize parametersJsonSchema for defining their function parameters. This change improves the flexibility and compatibility of tool handling within the framework, allowing for a broader range of tool specifications to be processed correctly. The update also includes minor code readability improvements and robust testing to ensure the new functionality works as expected.

Highlights

• MCP Tool Support: Introduced support for MCP (Multi-Cloud Platform) tools that define their parameters using parametersJsonSchema within LangChain4j.
• Flexible Schema Handling: The system now intelligently handles parametersJsonSchema which can be provided either as a raw JSON object (Map) or as a pre-parsed Schema object, converting it to a Schema for consistent processing.
• Improved Tool Specification Logic: Refactored the toToolSpecifications method to prioritize parametersJsonSchema for defining tool parameters, falling back to the existing parameters if parametersJsonSchema is not present.
• Enhanced Test Coverage: Added comprehensive unit tests to validate the correct handling of MCP tools with parametersJsonSchema in both Map and Schema formats, ensuring robustness and reliability.

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[gemini-code-assist]

Code Review

This pull request introduces support for MCP tools with parametersJsonSchema in LangChain4j, which is a valuable enhancement. The implementation correctly prioritizes parametersJsonSchema and handles both Schema objects and other object types that need conversion. The accompanying tests are thorough and cover the new logic well. I have one suggestion to improve the efficiency of the schema conversion logic by using ObjectMapper.convertValue().

[gemini-code-assist]

For efficiency and conciseness, you can directly convert the jsonSchemaObj to a Schema object using ObjectMapper.convertValue(). This avoids the intermediate step of serializing to a JSON string and then deserializing back.

Suggested change

	ObjectMapper adkMapper = JsonBaseModel.getMapper();
	String jsonSchemaStr = adkMapper.writeValueAsString(jsonSchemaObj);
	schema = adkMapper.readValue(jsonSchemaStr, Schema.class);
	schema = JsonBaseModel.getMapper().convertValue(jsonSchemaObj, Schema.class);