Fix CFG node duplication causing missing unboxing NPE warnings

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This PR fixes a bug in the Control Flow Graph (CFG) generation that prevented the Checker Framework from reporting unboxing NPE warnings for array access expressions like int x = nullableIntegerArray[0].

Problem

The issue was in CFGTranslationPhaseOne.visitArrayAccess() which incorrectly added the same ArrayAccessNode three times to the CFG:

1. extendWithNode(arrayAccess) - as a regular node
2. extendWithNodeWithException(arrayAccess, arrayIndexOutOfBoundsExceptionType) - with AIOOBE
3. extendWithNodeWithException(arrayAccess, nullPointerExceptionType) - with NPE

When translateAssignment() later inserted unboxing nodes (like .intValue() calls), they were placed after the first occurrence. This caused the extra copies of array[0] to appear after the unboxing operation in the CFG, making the checker incorrectly conclude that array[0] was non-null.

Example

void f(@Nullable Integer[] array) { 
    int x = array[0]; // Should warn about unboxing.of.nullable but didn't
}

Before this fix, the CFG looked like:

• RegularBlock([x, array, 0, array[0]])
• ExceptionBlock(array[0].intValue) - NullPointerException
• ExceptionBlock(array[0].intValue()) - RuntimeException+Error
• ExceptionBlock(array[0]) - ArrayIndexOutOfBoundsException ← Extra copy after unboxing
• ExceptionBlock(array[0]) - NullPointerException ← Extra copy after unboxing
• RegularBlock([x = array[0].intValue()])

Solution

The fix uses extendWithNodeWithExceptions() (plural) with a set containing both exception types instead of multiple separate calls:

Set<TypeMirror> exceptions = new HashSet<>();
exceptions.add(arrayIndexOutOfBoundsExceptionType);
exceptions.add(nullPointerExceptionType);
extendWithNodeWithExceptions(arrayAccess, exceptions);

This creates a single CFG node with proper exception handling, allowing unboxing warnings to be generated correctly.

Additional Fixes

Similar node duplication issues were fixed in:

• visitCompoundAssignment() for integer division/remainder operations
• visitBinary() for integer division/remainder operations

These operations were incorrectly calling both extendWithNodeWithException() for arithmetic exceptions and then extendWithNode() at the end of the method.

Fixes #7229.

Warning

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• central.sonatype.com
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -Xmx2g -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/gradle-daemon-main-9.0.0.jar -javaagent:/home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/agents/gradle-instrumentation-agent-9.0.0.jar org.gradle.launcher.daemon.bootstrap.GradleDaemon 9.0.0 (dns block)
• groovy.jfrog.io
  • Triggering command: /usr/lib/jvm/temurin-17-jdk-amd64/bin/java --add-opens=java.base/java.lang=ALL-UNNAMED --add-opens=java.base/java.lang.invoke=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.api=ALL-UNNAMED --add-exports=jdk.compiler/com.sun.tools.javac.util=ALL-UNNAMED --add-opens=java.base/java.util=ALL-UNNAMED --add-opens=java.prefs/java.util.prefs=ALL-UNNAMED --add-opens=java.base/java.nio.charset=ALL-UNNAMED --add-opens=java.base/java.net=ALL-UNNAMED --add-opens=java.base/java.util.concurrent=ALL-UNNAMED --add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED --add-opens=java.xml/javax.xml.namespace=ALL-UNNAMED -Xmx2g -Dfile.encoding=UTF-8 -Duser.country -Duser.language=en -Duser.variant -cp /home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/gradle-daemon-main-9.0.0.jar -javaagent:/home/REDACTED/.gradle/wrapper/dists/gradle-9.0.0-bin/d6wjpkvcgsg3oed0qlfss3wgl/gradle-9.0.0/lib/agents/gradle-instrumentation-agent-9.0.0.jar org.gradle.launcher.daemon.bootstrap.GradleDaemon 9.0.0 (dns block)

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