Describe the PR

This PR fixes a parsing issue where the PMD Java parser failed to parse switch expressions when used inside a lambda that's passed to a super() constructor call.

The Root Cause

In ConstructorBlock, the grammar used LOOKAHEAD(ExplicitConstructorInvocation()) which performed a full syntactic lookahead of the entire production, including the ArgumentList(). When the argument list contained complex expressions like lambdas with switch expressions (using case X -> value syntax), the lookahead would fail due to the complexity of parsing nested constructs during lookahead.

This caused the parser to fall back to treating super(...) as a regular statement, where super is expected to be followed by . or :: (for member access or method reference), resulting in the error:

Parse exception at line 10, column 10: Encountered "(". Was expecting one of: "." "::"

The Fix

Introduced a new lightweight lookahead production ExplicitCtorInvocLookahead() that only recognizes the structural pattern of explicit constructor invocations without parsing the full argument list:

• this( / super( for simple calls
• <TypeArgs>this( / <TypeArgs>super( for calls with type arguments
• qualifier.super( / qualifier.<TypeArgs>super( for qualified super calls

Also added PrimaryExpressionNoSuperThis() helper production to handle qualified super calls like Outer.this.super() and new Outer().super().

Related issues

• Fixes [java] Parser fails to parse switch expressions in super() constructor calls #6234

Ready?

• Added unit tests for fixed bug/feature
• Passing all unit tests
• Complete build ./mvnw clean verify passes (checked automatically by github actions)
• Added (in-code) documentation (if needed)