code: protected final Property getRequiredProperty(String name) throws ConstraintViolationException {
          Property p = getProperties().getProperty(name);
          if (p == null) {
              throw new ConstraintViolationException(String.format("Missing %s property", name));
          }
          return p;
      }
docs: Convenience method for retrieving a required named property.
  
  @param name name of the property to retrieve
  @return the first matching property in the property list with the specified name
  @throws ConstraintViolationException when a property is not found