[FLUSS-3628] Fix primary key hashCode contract

[wolfkill]

What changed

Schema.PrimaryKey.hashCode() now uses the same field set as equals().

Previously, equals() compared only columnNames, but hashCode() also included super.hashCode(), which is object-identity based. Two equal PrimaryKey instances could therefore produce different hash codes and behave incorrectly in hash-based collections.

Validation

• RED: JAVA_HOME=/Users/cc/Library/Java/JavaVirtualMachines/corretto-18.0.2/Contents/Home mvn -pl fluss-common -am -Dtest=TableSchemaTest#testPrimaryKeyHashCodeMatchesEquals -DfailIfNoTests=false test
  • failed before the fix with different hash codes for two equal Schema.PrimaryKey instances
• GREEN: same targeted test passed after the fix
• JAVA_HOME=/Users/cc/Library/Java/JavaVirtualMachines/corretto-18.0.2/Contents/Home mvn -pl fluss-common -am -Dtest=TableSchemaTest -DfailIfNoTests=false test
  • Tests run: 9, Failures: 0, Errors: 0, Skipped: 0
• JAVA_HOME=/Users/cc/Library/Java/JavaVirtualMachines/corretto-18.0.2/Contents/Home mvn -pl fluss-common -am -DfailIfNoTests=false test
  • Tests run: 1729, Failures: 0, Errors: 0, Skipped: 1
  • reactor result: BUILD SUCCESS
• git diff --check

[wolfkill]

Closing this as a duplicate.

After creating the PR, I was able to load the issue comments and found that #3629 had already been opened for FLUSS-3628. Sorry for the noise.