code: public static String enumValues(Class<?> enumClass) {
      Preconditions.checkNotNull(enumClass, "enumClass cannot be null");
      Preconditions.checkState(enumClass.isEnum(), "enumClass must be an enum.");
      return Joiner.on(", ").join(enumClass.getEnumConstants());
    }
docs: Method is used to return the values for an enum.
  
  @param enumClass Enum class to return the constants for.
  @return Returns a comma seperated string of all of the values in the enum.