Retain load-bearing type witness in select position in UnnecessaryExplicitTypeArguments

[knutwannheden]

Motivation

UnnecessaryExplicitTypeArguments removes an explicit type witness from a generic method invocation even when that witness is load-bearing — specifically when the invocation is the select (receiver) of another method invocation. In that position there is no target type to drive type inference, so the witness is required, and removing it produces non-compiling code.

Observed in the wild on rewrite-spring's ImplicitWebAnnotationNames:

// before — compiles
J.VariableDeclarations.NamedVariable namedVariable =
        varDecsCursor.<J.VariableDeclarations>getValue().getVariables().get(0);

// after recipe — does NOT compile
J.VariableDeclarations.NamedVariable namedVariable =
        varDecsCursor.getValue().getVariables().get(0);

Cursor#getValue() is declared <T> T getValue(). With the <J.VariableDeclarations> witness removed and the result immediately chained into .getVariables(), there is no target type, so T infers to Object, and Object has no getVariables() method.

Summary

• Split the enclosing instanceof J.MethodInvocation handling into select vs. argument positions (enclosingMethod.getSelect() == method).
• In select position the enclosing call provides no target type, so the witness is retained unless the type variables are inferable from the call's own arguments.
• Extracted that inference check into canInferTypeArgumentsFromArguments(...), reused by shouldRetainOnStaticMethod so existing static-method and argument-position behavior is unchanged.

Test plan

• Added retainsWitnessWhenResultIsSelectOfMethodInvocation reproducing the chained-call case (recipe makes no change).
• Full UnnecessaryExplicitTypeArgumentsTest suite passes, including the pre-existing select-position case GenericClass.<T>typedBuilderWithClass(clazz).build() where the witness is still correctly removed (type variable inferable from the Class<T> argument).