@Override
  public Connection toConnection() {
    ConnectionOverAsyncConnection c = this.conn;
    if (c != null) {
      return c;
    }
    synchronized (this) {
      c = this.conn;
      if (c != null) {
        return c;
      }
      c = new ConnectionOverAsyncConnection(this);
      this.conn = c;
    }
    return c;
  }
If choreService has not been created yet, create the ChoreService.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/AsyncConnectionImpl.java