Passing Conf object to KryoDecorator

[reiabreu]

Important

Disclaimer: This PR and its description were generated using Gemini CLI, an AI-powered developer tool.

Problem Statement
Currently, the IKryoDecorator interface only provides access to the Kryo instance. This prevents users from registering custom serializers that require metadata or schemas stored in the topology configuration. Users were previously
forced to use brittle workarounds, such as reading configuration from the local filesystem at worker startup.

Proposed Changes
This PR updates the IKryoDecorator interface to provide access to the topology configuration map, allowing for more dynamic and configuration-driven serialization logic.

1. Interface Evolution (IKryoDecorator.java):
   • Added a new default method: void decorate(Kryo k, Map<String, Object> conf).
   • Deprecated the legacy void decorate(Kryo k) method.
   • The new method calls the deprecated one by default to maintain source and binary compatibility for existing implementations.
2. Serialization Logic Update (SerializationFactory.java):
   • Updated the getKryo factory method to pass the topology configuration (conf) when invoking decorators.
3. Testing and Validation:
   • Added a new test case test_registers_decorator_with_conf to SerializationFactoryTest.java.
   • Verified that a custom decorator can successfully retrieve values from the configuration map to perform conditional registrations.

Backward Compatibility

• Binary Compatibility: Existing compiled decorators will continue to work without modification as the new method is a Java default method.
• Source Compatibility: Existing source code will compile without changes, although users will receive a deprecation warning if they continue to implement the single-parameter decorate method.

Verification Results

• Ran mvn test -Dtest=SerializationFactoryTest -pl storm-client — SUCCESS
• Verified that TestKryoDecorator.java (using the old signature) still functions as expected.
• Verified that Javadoc meets project Checkstyle requirements.

[reiabreu]

@sambenas Just be mindful that the file has to serializable in order for the Conf map to be uploaded.
Once merged, this will be out in the next release.
Thank you