code: @Override
      public List<T> getList() {
          if (isCacheEnabled) {
              if (cachedResult == null) {
                  cachedResult = makeUnmodifiableUniqueList();
              }
              return cachedResult;
          } else {
              return makeUnmodifiableUniqueList();
          }
      }
docs: Returns the list that this ListHolder backs.