Sample testcase attached.
Because of this behavior, WsGen is generating incorrect classes when the WebServices it compiles uses java.xml.ws.Holder<T> as WebParam, and many TCK tests are failing.

In the testcase, for
public void testHolder(Holder<String> param) { }

public void visitMethodDeclaration(MethodDeclaration method) {
                System.out.println(method.getSimpleName());
                for (ParameterDeclaration param : method.getParameters()) {
                    TypeMirror type = param.getType();
                    System.out.println(type);
                    if (type instanceof DeclaredType) {
                        Collection<TypeMirror> argTypes = ((DeclaredType) type).getActualTypeArguments();
                        System.out.println(argTypes.size());
                        if (argTypes.size() == 1) {
                            TypeMirror mirror = argTypes.iterator().next();
                            System.out.println("argsTypes.iterator().next(): " + mirror);
                        }
                    }
                }
            }

argTypes.size is 0 when the sources are compiled with debug option. We expect the argTypes.iterator.next() to be String.

Output Without debug option:
test.Bar
testHolder
ann.Holder<java.lang.String>
1
argsTypes.iterator().next(): java.lang.String

Output With debug option:
test.Bar
testHolder
ann.Holder
0