Test Coverage Analysis for GoogleOpenAISchema

Current Issues:
- 6 uncovered lines in src/llm_openai_schema_defs.jl
- Patch coverage at 14.29%

Implementation Analysis:
1. GoogleProvider struct (lines 219-223)
   - Basic struct definition, likely covered
   - auth_header method (lines 225-227) might be uncovered

2. create_chat method (lines 229-244)
   - Key lines that might be uncovered:
     * Line 235: api_key override logic
     * Line 237: GoogleProvider instantiation
     * Lines 238-243: OpenAI.openai_request call

3. create_embeddings method (lines 415-429)
   - Similar pattern to create_chat
   - Potential uncovered lines:
     * Line 421: api_key override logic
     * Line 422: GoogleProvider instantiation
     * Lines 423-428: OpenAI.openai_request call

Hypotheses for Coverage Issues:
1. Streaming callback paths not tested
   - We're using openai_request directly, which might have different behavior
   - Solution: Add tests for streaming scenarios

2. Error handling paths not tested
   - No tests for API errors or invalid responses
   - Solution: Add tests with mock error responses

3. Provider instantiation edge cases
   - GoogleProvider creation with different URL combinations not tested
   - Solution: Add tests with various URL configurations

4. API key override logic not fully tested
   - Need to test all combinations of empty/non-empty GOOGLE_API_KEY
   - Solution: Expand current tests to cover more scenarios

5. Request parameter handling not fully tested
   - Different combinations of optional parameters not tested
   - Solution: Add tests with various kwargs combinations

Most Likely Issue:
Hypothesis #4 seems most likely - our tests don't fully exercise the API key override logic in both create_chat and create_embeddings methods. The current tests only check basic scenarios, but we need to test edge cases and different combinations of API keys.

Action Plan:
1. Add tests for API key override edge cases
2. Add tests for different URL configurations
3. Add tests for error scenarios
4. Add tests for streaming callbacks
5. Add tests for various kwargs combinations
