[BugFix] BedrockConverse: Fix calling tools with empty arguments

[dpernes]

Description

PR #18781 introduced a bug where tool calls with empty arguments were being skipped (see this comment for a detailed description). This PR fixes it.

Version Bump?

Did I bump the version in the pyproject.toml file of the package I am updating? (Except for the llama-index-core package)

• Yes
• No

Type of Change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

Your pull-request will likely not be merged unless it is covered by some form of impactful unit testing.

• I added new unit tests to cover this change
• I believe this change is already covered by existing unit tests

Suggested Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have added Google Colab support for the newly added notebooks.
• My changes generate no new warnings
• 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 ran uv run make format; uv run make lint to appease the lint gods

[pazevedo-hyland]

Awesome I think this will also fix this: #18449

[dpernes]

Awesome I think this will also fix this: #18449

I don't think so, unfortunately. #18449 is a different issue: a ValidationException is (possibly erroneously) raised when the model output contains a tool call without any accompanying text.

[AstraBert]

Lgtm!