code: public static <T> T notNull(T value, String message) {
          if (value == null) {
              throw new NullPointerException(message);
          }
          return value;
      }
docs: Checks that the given value is not {@code null}, using the given message
  as the exception message if an exception is thrown.
  
  @param value object reference to check
  @param message message to use if {@code value} is {@code null}
  @return the passed-in value, if not {@code null}
  @throws NullPointerException if {@code value} is {@code null}