code: public static void instanceOf(final Object input, Class<?> classType, final String inputName) {
          notNull(input, "input");
          notNull(classType, "classType");
  
          if (!classType.isInstance(input)) {
              throw new IllegalArgumentException("Expecting " + maskNullArgument(inputName) + " to an instance of " + classType.getName() + ".");
          }
      }
docs: Check that an input of a given class
  @param input the input
  @param classType the class to check for
  @param inputName the name of the input