static Integer getHttp2PortStr(ZNRecord znRecord) {
    String http2PortStr = znRecord.getSimpleField(HTTP2_PORT_STR);
    return http2PortStr == null ? null : Integer.valueOf(http2PortStr);
  }
Get the http2 port associated with the given instance (if any).
@param znRecord the {@link ZNRecord} associated with the interested instance.
@return the http2 port associated with the given instance.
ambry-clustermap/src/main/java/com/github/ambry/clustermap/ClusterMapUtils.java