code: public static StandardSubjectBuilder assertWithMessage(String format, Object... args) {
      return assert_().withMessage(format, args);
    }
docs: Returns a {@link StandardSubjectBuilder} that will prepend the formatted message using the
  specified arguments to the failure message in the event of a test failure.
  
  <p><b>Note:</b> the arguments will be substituted into the format template using {@link
  com.google.common.base.Strings#lenientFormat Strings.lenientFormat}. Note this only supports
  the {@code %s} specifier.
  
  @throws IllegalArgumentException if the number of placeholders in the format string does not
  equal the number of given arguments