code: public static boolean isProperClass(Class<?> clazz) {
  		int mods = clazz.getModifiers();
  		return !(Modifier.isAbstract(mods) || Modifier.isInterface(mods) || Modifier.isNative(mods));
  	}
docs: Checks, whether the class is a proper class, i.e. not abstract or an interface, and not a primitive type.
  
  @param clazz The class to check.
  @return True, if the class is a proper class, false otherwise.