fix: Avoid ClassCastException and reduce copy/pasta 🍝 in FunctionTool

[vorburger]

Prompted by #487 (comment).

[gemini-code-assist]

Summary of Changes

Hello @vorburger, 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 refactors the FunctionTool class to improve code organization, reduce duplication, and enhance robustness in argument processing. By extracting common argument building and type resolution logic into dedicated helper methods, the PR makes the call and callLive methods cleaner and more resilient to various input scenarios, addressing potential runtime exceptions related to type casting and null references.

Highlights

• Refactoring for Reusability: The logic for building method arguments, previously duplicated in call and callLive methods, has been extracted into a new private helper method named buildArguments. This significantly reduces code duplication and improves maintainability.
• Improved Type Handling: A new private static helper method, getTypeClass, was introduced to correctly resolve the Class type from a java.lang.reflect.Type object, specifically handling both simple Class types and ParameterizedTypes. This centralizes type resolution logic and prevents potential ClassCastExceptions.
• Enhanced Robustness: Added a null check for invocationContext within the buildArguments method when handling inputStream parameters, preventing potential NullPointerExceptions in scenarios where invocationContext might not be provided.

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[gemini-code-assist]

Code Review

This pull request does a great job of refactoring the FunctionTool class to eliminate duplicated code by introducing a buildArguments method. This significantly improves the maintainability and clarity of the call and callLive methods. The change also correctly addresses a potential ClassCastException by introducing the getTypeClass helper, making type handling for list parameters more robust. Overall, this is a solid improvement to the codebase. I have one minor suggestion to further improve readability.