@Override
  public ConnectionRegistry create(URI uri, Configuration conf, User user) throws IOException {
    assert getScheme().equals(uri.getScheme());
    LOG.debug("connect to hbase cluster with rpc bootstrap servers='{}'", uri.getAuthority());
    Configuration c = new Configuration(conf);
    c.set(RpcConnectionRegistry.BOOTSTRAP_NODES, uri.getAuthority());
    return new RpcConnectionRegistry(c, user);
  }
Connection registry creator implementation for creating {@link RpcConnectionRegistry}.
hbase-client/src/main/java/org/apache/hadoop/hbase/client/RpcConnectionRegistryURIFactory.java