@Test
  public void testWarmUpConnectionsSslAndPlainText() {
    // warm up plain-text connections with SSL enabled nodes.
    doTestWarmUpConnections(localSslDataNodes, MAX_PORTS_PLAIN_TEXT, PortType.PLAINTEXT);
    // enable SSL to local DC.
    for (DataNodeId dataNodeId : localSslDataNodes) {
      ((MockDataNodeId) dataNodeId).setSslEnabledDataCenters(Collections.singletonList(
          sslEnabledClusterMap.getDatacenterName(sslEnabledClusterMap.getLocalDatacenterId())));
    }
    // warm up SSL connections.`
    doTestWarmUpConnections(localSslDataNodes, MAX_PORTS_SSL, PortType.SSL);
  }
Test {@link SocketNetworkClient#warmUpConnections(List, int, long, List)}
ambry-network/src/test/java/com/github/ambry/network/SocketNetworkClientTest.java