code: public String getSubject(String language) {
          Subject subject = getMessageSubject(language);
          return subject == null ? null : subject.subject;
      }
docs: Returns the subject corresponding to the language. If the language is null, the method result
  will be the same as {@link #getSubject()}. Null will be returned if the language does not have
  a corresponding subject.
  
  @param language the language of the subject to return.
  @return the subject related to the passed in language.