docs: public final void configure(Properties props, FormatterBuilder formatterBuilder)
      {
          Map<URI, ImporterConfig> configs = m_factory.createImporterConfigurations(props, formatterBuilder);
          m_configs = new ImmutableMap.Builder<URI, ImporterConfig>()
                  .putAll(configs)
                  .putAll(Maps.filterKeys(m_configs, not(in(configs.keySet()))))
                  .build();
      }