Agent/Tool Parsing Fixes

[pyek-bot]

Description

Fixes the following issues:

1. When the LLM responds with empty content, then there is no actual string to be processed. This by default falls back to tool use, however in tool use block we do a .getFirst().get() assuming there is a tool use block in the response. This PR adds a simple check to avoid such NPEs. Look at [BUG] ChatAgent fails while parsing LLMOutput #4136 for more details. There is another issue where the LLM responds with tool_use but no tool use block, for this we need to raise a ticket to the bedrock team.
2. When steps returned by LLM contains a , the parsing breaks. This is due to a double conversion of json array to string and string to array. This has been fixed in this PR by directly returning the original json.
3. When tool parameters contain nested json, the extractInputParameters method fails due to expecting a Map<String, String> . This has been fixed and the exception made clearer as we fall back to string by default.

For more details look at the issues mentioned below

Related Issues

Resolves #4135
Resolves #4137
Partially resolves #4136

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

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