code: static void assertInstantiable(Class<?> c) {
      int modifiers = c.getModifiers();
      if (Modifier.isInterface(modifiers)) {
        throw new UnsupportedOperationException("Interface can't be instantiated! Interface name: " + c.getName());
      }
      if (Modifier.isAbstract(modifiers)) {
        throw new UnsupportedOperationException("Abstract class can't be instantiated! Class name: " + c.getName());
      }
    }
docs: Check if the class can be instantiated by unsafe allocator. If the instance has interface or abstract modifiers
  throw an {@link java.lang.UnsupportedOperationException}
  @param c instance of the class to be checked