@Override
  public Future<Void> mergeRegionsAsync(byte[][] nameOfRegionsToMerge, boolean forcible)
    throws IOException {
    return admin.mergeRegions(Arrays.asList(nameOfRegionsToMerge), forcible);
  }
The {@link Admin} implementation which is based on an {@link AsyncAdmin}.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AdminOverAsyncAdmin.java