code: public void assertStringNotEmpty(String propertyValue, String propertyName) {
          if (StringUtils.isNullOrEmpty(propertyValue)) {
              problemReporter.report(new Problem(this, String.format("%s is a required property.", propertyName)));
          }
      }
docs: Asserts the string is not null and not empty, reporting to {@link ProblemReporter} with this context if it is.
  
  @param propertyValue Value to assert on.
  @param propertyName  Name of property.