code: public static void checkArgument(boolean b, @Nullable String errorMessageTemplate, char p1) {
      if (!b) {
        throw new IllegalArgumentException(format(errorMessageTemplate, p1));
      }
    }
docs: Ensures the truth of an expression involving one or more parameters to the calling method.
  
  <p>See {@link #checkArgument(boolean, String, Object...)} for details.