code: private static boolean isNumericType(Class<?> c) {
      return Number.class.isAssignableFrom(c)
          || double.class == c
          || float.class == c
          || long.class == c
          || int.class == c
          || short.class == c
          || byte.class == c;
    }
docs: Returns true if {@code c} can be assigned to a number.