code: @Override
      public void initialize(BackendInstanceSpec config)
              throws BackendInitializationException {
          super.initialize(config);
          if (this.mappingsFactory == null) {
              setMappingsFactory(null);
          }
          this.relationalDatabaseSpecBuilder
                  = createRelationalDatabaseSpecBuilder();
      }
docs: Collects the database connection information specified in this backend's
  configuration, and uses it to try and get a SQL generator with which to
  generate database queries.
  
  @param config the {@link BackendInstanceSpec} that specifies this
  backend's configuration parameters.
  
  @throws DataSourceBackendInitializationException if bad database
  connection information was provided or a SQL generator that is compatible
  with the database and available drivers is not available.