code: private static void initializePropertiesIfNeeded() {
          if (translationResources != null) {
              return;
          }
          String lastException = "";
          try {
              translationResources = new Properties();
              ClassLoader classLoader = ClassLoader.getSystemClassLoader();
              translationResources.load(classLoader.getResourceAsStream(
                      propertiesFileName));
          } catch (Exception exception) {
              lastException = exception.toString() + "\n----\n" + exception.getMessage();
          }
          if (translationResources == null) {
              throw new RuntimeException("TranslationSource.initializePropertiesIfNeeded()"
                      + "Could not load TranslationResources.properties file.\n"
                      + "The exception follows:\n" + lastException);
          }
      }
docs: initializePropertiesIfNeeded, If needed, this will initialize the translation properties. If
  the translation properties have already been initialized, then this will do nothing.