code: public T fetchSingleOrNull() throws InstantiationException, IllegalAccessException, SQLException {
          if (!finished) {
              T result = primitive ? fetchSinglePrimitiveInternal() : fetchSingleInternal();
              next();
              return result;
          } else {
              return null;
          }
      }
docs: Fetches single entity or null.
  
  @return Single entity if result set have one more, otherwise null.
  @throws InstantiationException
  @throws IllegalAccessException
  @throws SQLException