docs: public static boolean isCallableConstructor(ExecutableElement constructor) {
      if (constructor.getModifiers().contains(Modifier.PRIVATE)) {
        return false;
      }
      TypeElement type = (TypeElement) constructor.getEnclosingElement();
      return type.getEnclosingElement().getKind() == ElementKind.PACKAGE
          || type.getModifiers().contains(Modifier.STATIC);
    }