[CALCITE-7558] Lattice.Measure.compareTo() collapses distinct aggregates that share the same name

[1fanwang]

Jira Link

CALCITE-7558

Changes Proposed

A lattice can contain a built-in aggregate and a user-defined aggregate with the same name. Lattice.Measure.compareTo() treated those measures as equal even when SqlOperator.equals() did not, so the builder's TreeSet silently discarded one of them. Current main retains one of three unequal measures in the regression; this branch retains all three.

The natural order still compares arguments, aggregate name, and the distinct flag in the same order as before. Aggregate kind and implementation class now break only ties that previously collapsed unequal measures.

Testing

$ SOURCE=core/src/main/java/org/apache/calcite/materialize/Lattice.java
$ git checkout c46c70cb26 -- "$SOURCE"
$ JAVA_HOME=$(/usr/libexec/java_home -v 21) ./gradlew :core:test \
    --tests 'org.apache.calcite.materialize.LatticeSuggesterTest.testMeasureNaturalOrderingKeepsDistinctAggregatorsWithSameName' \
    --no-daemon --console=plain
Expected: a collection with size <3>
     but: collection size was <1>

$ git checkout a8981422fa -- "$SOURCE"
$ JAVA_HOME=$(/usr/libexec/java_home -v 21) ./gradlew :core:test \
    --tests 'org.apache.calcite.materialize.LatticeSuggesterTest.testMeasureNaturalOrderingKeepsDistinctAggregatorsWithSameName' \
    --no-daemon --console=plain
0.1sec, 1 completed, 0 failed, 0 skipped
BUILD SUCCESSFUL

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
85.7% Coverage on New Code
0.0% Duplication on New Code

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