fix: widen Integer to Long in castValue() for boxed Long parameter

[jjhz]

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Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Closes: Bug: FunctionTool silently returns generic error when tool has a boxed Long parameter and model returns a small integer #1289

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.
• All unit tests pass locally.

Two new tests added to FunctionToolTest:

• call_withPrimitiveLongParam_whenModelProvidesInteger_succeeds — confirms primitive long was never broken (Java reflection auto-widens int → long); serves as a regression guard.
• call_withBoxedLongParam_whenModelProvidesInteger_succeeds — directly reproduces the bug: passes Integer(42) as the arg for a boxed Long parameter (exactly what Jackson produces when deserializing the model's small integer), and asserts the tool returns 42L correctly.

Tests run: 60, Failures: 0, Errors: 0, Skipped: 0

Manual End-to-End (E2E) Tests:

The bug is fully exercised by the unit tests above, which simulate exactly what the ADK framework does at runtime: Jackson deserializes a small JSON integer as Integer, the framework passes it unchanged into tool.runAsync(), and castValue() must widen it to Long before reflection invokes the tool method. No additional E2E setup is required to observe the fix.

Checklist

• I have read the CONTRIBUTING.md document.
• My pull request contains a single commit.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

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[hemasekhar-p]

Hi @jjhz, thank you for your contribution! We appreciate you taking the time to submit this pull request. Currently this PR is under review by our team, we will keep you posted if any additional information is required. thank you.

[hemasekhar-p]

@krwc, Could you please review this PR.