@Override
  public int getHttp2Port() {
    if (hasHttp2Port()) {
      return ports.get(PortType.HTTP2).getPort();
    } else {
      throw new IllegalStateException("No HTTP2 port exists for the Data Node " + hostname + ":" + portNum);
    }
  }
Gets the DataNode's HTTP2 port number.

@return Port number upon which to establish an HTTP2 connection with the DataNodeId.
@throws IllegalStateException Thrown if no HTTP2 port exists.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/DataNode.java