gravitino

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# Copilot Instructions for Gravitino

## Critical Rules
- **Java Imports**: ALWAYS use standard imports. NEVER use Fully Qualified Class Names (FQN) inside methods unless absolutely necessary for collision resolution.
  - BAD: `org.apache.gravitino.NameIdentifier id = ...`
  - GOOD: `NameIdentifier id = ...` (add `import org.apache.gravitino.NameIdentifier;`)
- **Coding Style**: Strict adherence to Google Java Style.
- **Testing**:
  - EVERY change must have a corresponding test.
  - Do NOT modify existing tests unless the logic has fundamentally changed.
  - Use `TestXxx` prefix for test classes (e.g., `TestMetalake`).
- **Dependencies**: Do NOT add new dependencies without explicit user request.
- **Documentation**: JavaDoc is required for all public APIs.

## Language Specifics
- **Java**:
  - Use `@Nullable` for optional fields/params.
  - Avoid `System.out.println`. Use SLF4J logging.
  - Use `Preconditions.checkArgument` for validation.
  - **Class Member Ordering**: Follow the order:
    1. `static` constants (e.g., `LOG`).
    2. `static` fields.
    3. Instance fields.
    4. Constructors.
    5. Methods (Group by visibility, putting `private` methods at the end).
- **Python**:
  - Follow PEP 8.
  - Type hints are mandatory.

## General
- **Brevity**: Write concise, efficient code. Avoid boilerplate where possible.
- **Safety**: Always check for nulls and handle exceptions specifically (no generic `catch (Exception e)`).

## Review Checklist (Keep It Short)
- **License/Legal**: New files must include Apache License 2.0 header; dependency/license changes must update LICENSE/NOTICE as required.
- **Compatibility**: Avoid breaking changes unless explicitly justified and documented (including migrations when needed).
- **Java hygiene**: No wildcard imports; close resources (try-with-resources); do not leave TODO/FIXME without an issue reference.
- **Security**: No hardcoded secrets; validate external inputs; prevent injection/path traversal/SSRF where applicable; do not log sensitive data.
- **APIs**: Public APIs require JavaDoc; REST APIs must enforce authentication/authorization and return correct HTTP status codes with consistent error payloads.
- **Testing**: Cover error paths and edge cases; keep tests isolated/non-flaky; Docker-dependent tests must be tagged with `@Tag("gravitino-docker-test")`.

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