code: @BetaApi
    public final SerialPortOutput getSerialPortOutputInstance(
        ProjectZoneInstanceName instance, Integer port, String start) {
  
      GetSerialPortOutputInstanceHttpRequest request =
          GetSerialPortOutputInstanceHttpRequest.newBuilder()
              .setInstance(instance == null ? null : instance.toString())
              .setPort(port)
              .setStart(start)
              .build();
      return getSerialPortOutputInstance(request);
    }
docs: Returns the last 1 MB of serial port output from the specified instance.
  
  <p>Sample code:
  
  <pre><code>
  try (InstanceClient instanceClient = InstanceClient.create()) {
  ProjectZoneInstanceName instance = ProjectZoneInstanceName.of("[PROJECT]", "[ZONE]", "[INSTANCE]");
  Integer port = 0;
  String start = "";
  SerialPortOutput response = instanceClient.getSerialPortOutputInstance(instance, port, start);
  }
  </code></pre>
  
  @param instance Name of the instance scoping this request.
  @param port Specifies which COM or serial port to retrieve data from.
  @param start Returns output starting from a specific byte position. Use this to page through
  output when the output is too large to return in a single request. For the initial request,
  leave this field unspecified. For subsequent calls, this field should be set to the next
  value returned in the previous call.
  @throws com.google.api.gax.rpc.ApiException if the remote call fails