@Override
  public IndexRepository getRepository(Region region, Object key, Object callbackArg)
      throws BucketNotFoundException {
    BucketRegion userBucket = userRegion.getBucketRegion(key, callbackArg);
    if (userBucket == null) {
      throw new BucketNotFoundException("User bucket was not found for region " + region + "key "
          + key + " callbackarg " + callbackArg);
    }

    return getRepository(userBucket.getId());
  }
The user region for this index
geode-lucene/src/main/java/org/apache/geode/cache/lucene/internal/PartitionedRepositoryManager.java