code: public boolean isMandatory(String propName) {
          if (mandatoryProperties == null) {
              setMandatoryPropertyNames();
          }
          if (mandatoryProperties.contains(propName)) {
              return true;
          } else {
              return false;
          }
      }
docs: Returns true if the provided property is a mandatory property; false, otherwise.
  
  @return
  returned object is {@link boolean}