Enhance test coverage across Spring AI modules with comprehensive edge cases

[alxkm]

Summary
This PR significantly improves test coverage across multiple Spring AI modules by adding comprehensive edge case testing, error handling validation, and real-world scenario coverage.

Modules Enhanced

ZhiPuAI Chat Model (ChatCompletionRequestTests)

• Added prompt options override validation
• Enhanced tool callback testing with assertions
• Added streaming functionality tests

ID Generation (IdGeneratorProviderTest)

• Added metadata variation testing
• Enhanced UUID format validation with proper structure checks
• Added consistency testing across multiple calls
• Added metadata order independence verification
• Added sensitivity testing for minor content changes
• Added multi-instance consistency validation

Observability Helper (ObservabilityHelperTests)

• Added null input error handling
• Enhanced special character support (quotes, newlines, tabs, backslashes)
• Added whitespace-only string handling
• Added mixed data type support (numbers, booleans, strings)
• Added ordered map testing with TreeMap
• Added complex object value handling
• Added consistency verification and empty key support

Ollama Embedding Model (OllamaEmbeddingModelTests)

• Added single input embedding test
• Enhanced null options handling
• Added multiple large input batch processing
• Added custom keepAlive format testing (seconds/hours)
• Added response metadata validation
• Added zero-length vector edge case
• Added builder validation tests

Ollama Retry Logic (OllamaRetryTests)

• Added first attempt success validation
• Enhanced non-transient error handling
• Added multi-message conversation testing
• Added custom options with retry scenarios
• Added empty response edge case handling

OpenAI Moderation API (OpenAiModerationApiBuilderTests)

• Added builder method chaining validation
• Enhanced instance creation verification

Text Reader (TextReaderTests)

• Added empty text handling
• Enhanced whitespace-only content processing
• Added multi-newline format support
• Added custom metadata preservation testing
• Added resource description handling
• Added consistency across multiple calls
• Added file extension edge cases

Typesense Vector Store (TypesenseVectorStoreBuilderTests)

• Added minimum embedding dimension validation
• Added single character collection name support

Key Improvements

• Error Handling: Comprehensive null input validation and exception testing
• Edge Cases: Empty content, whitespace-only strings, special characters, Unicode support
• Data Types: Mixed type handling, complex objects, large datasets
• Consistency: Multiple call verification, order independence, deterministic behavior
• Real-world Scenarios: Batch processing, retry logic, builder patterns, configuration validation

Impact

• Significantly improves test coverage across modules by addressing critical gaps in edge case handling, error conditions, and real-world usage scenarios
• Improves confidence in production reliability
• Ensures proper handling of edge cases and error conditions
• Validates critical functionality like ID generation consistency and retry mechanisms

Testing
All new tests pass and maintain compatibility with existing test patterns and assertion styles.

[markpollack]

Thanks @alxkm