code: private void resolveProperties() {
          if (arePropertiesResolved) {
              return;
          }
  
          Class<?> cl = forClass();
          isProxy = Proxy.isProxyClass(cl);
          isEnum = Enum.class.isAssignableFrom(cl);
          isSerializable = isSerializable(cl);
          isExternalizable = isExternalizable(cl);
  
          arePropertiesResolved = true;
      }
docs: Resolves the class properties, if they weren't already