code: private String parseMandatoryStringValue(final String path) throws Exception {
  
          final String value = parseOptionalStringValue(path);
          if (value == null) {
              throw new Exception();
          }
          return value;
      }
docs: Helper to read a mandatory String value.
  @param path The XML path of the element to read.
  @return The String value stored in the XML.
  @throws Exception thrown if the value could not be read.