@java.lang.Override
  public int getSerializedSize() {
    int size = memoizedSize;
    if (size != -1) return size;

    size = 0;
    if (httpMethod_
        != com.google.cloud.tasks.v2beta2.HttpMethod.HTTP_METHOD_UNSPECIFIED.getNumber()) {
      size += com.google.protobuf.CodedOutputStream.computeEnumSize(1, httpMethod_);
    }
    if (((bitField0_ & 0x00000001) != 0)) {
      size += com.google.protobuf.CodedOutputStream.computeMessageSize(2, getAppEngineRouting());
    }
    if (!com.google.protobuf.GeneratedMessageV3.isStringEmpty(relativeUrl_)) {
      size += com.google.protobuf.GeneratedMessageV3.computeStringSize(3, relativeUrl_);
    }
    for (java.util.Map.Entry<java.lang.String, java.lang.String> entry :
        internalGetHeaders().getMap().entrySet()) {
      com.google.protobuf.MapEntry<java.lang.String, java.lang.String> headers__ =
          HeadersDefaultEntryHolder.defaultEntry
              .newBuilderForType()
              .setKey(entry.getKey())
              .setValue(entry.getValue())
              .build();
      size += com.google.protobuf.CodedOutputStream.computeMessageSize(4, headers__);
    }
    if (!payload_.isEmpty()) {
      size += com.google.protobuf.CodedOutputStream.computeBytesSize(5, payload_);
    }
    size += getUnknownFields().getSerializedSize();
    memoizedSize = size;
    return size;
  }
<pre>
Payload.

The payload will be sent as the HTTP message body. A message
body, and thus a payload, is allowed only if the HTTP method is
POST or PUT. It is an error to set a data payload on a task with
an incompatible [HttpMethod][google.cloud.tasks.v2beta2.HttpMethod].
</pre>

<code>bytes payload = 5;</code>

@return The payload.
java-tasks/proto-google-cloud-tasks-v2beta2/src/main/java/com/google/cloud/tasks/v2beta2/AppEngineHttpRequest.java