docs: private static synchronized void storeSingleton() {
          // recheck that we need to run because field could have been
          // set since we decided to invoke this method but before we acquired
          // the lock on this object
          if (PERSON_DIR_NAME_FINDER_INSTANCE == null) {
              IPersonAttributeDao personAttributeDao =
                      PersonAttributeDaoLocator.getPersonAttributeDao();
              PERSON_DIR_NAME_FINDER_INSTANCE = new PersonDirNameFinder(personAttributeDao);
          }
      }