docs: public static boolean hasExplicitConstructor(AbstractASTTransformation xform, ClassNode cNode) {
          List<ConstructorNode> declaredConstructors = cNode.getDeclaredConstructors();
          for (ConstructorNode constructorNode : declaredConstructors) {
              // allow constructors added by other transforms if flagged as Generated
              if (hasAnnotation(constructorNode, GENERATED_TYPE)) {
                  continue;
              }
              if (xform != null) {
                  xform.addError("Error during " + xform.getAnnotationName() +
                          " processing. Explicit constructors not allowed for class: " +
                          cNode.getNameWithoutPackage(), constructorNode);
              }
              return true;
          }
          return false;
      }