@java.lang.Override
    public Builder mergeFrom(
        com.google.protobuf.CodedInputStream input,
        com.google.protobuf.ExtensionRegistryLite extensionRegistry)
        throws java.io.IOException {
      if (extensionRegistry == null) {
        throw new java.lang.NullPointerException();
      }
      try {
        boolean done = false;
        while (!done) {
          int tag = input.readTag();
          switch (tag) {
            case 0:
              done = true;
              break;
            case 8:
              {
                httpMethod_ = input.readEnum();
                bitField0_ |= 0x00000001;
                break;
              } // case 8
            case 18:
              {
                input.readMessage(
                    getAppEngineRoutingFieldBuilder().getBuilder(), extensionRegistry);
                bitField0_ |= 0x00000002;
                break;
              } // case 18
            case 26:
              {
                relativeUri_ = input.readStringRequireUtf8();
                bitField0_ |= 0x00000004;
                break;
              } // case 26
            case 34:
              {
                com.google.protobuf.MapEntry<java.lang.String, java.lang.String> headers__ =
                    input.readMessage(
                        HeadersDefaultEntryHolder.defaultEntry.getParserForType(),
                        extensionRegistry);
                internalGetMutableHeaders()
                    .getMutableMap()
                    .put(headers__.getKey(), headers__.getValue());
                bitField0_ |= 0x00000008;
                break;
              } // case 34
            case 42:
              {
                body_ = input.readBytes();
                bitField0_ |= 0x00000010;
                break;
              } // case 42
            default:
              {
                if (!super.parseUnknownField(input, extensionRegistry, tag)) {
                  done = true; // was an endgroup tag
                }
                break;
              } // default:
          } // switch (tag)
        } // while (!done)
      } catch (com.google.protobuf.InvalidProtocolBufferException e) {
        throw e.unwrapIOException();
      } finally {
        onChanged();
      } // finally
      return this;
    }
<pre>
App Engine HTTP request.

The message defines the HTTP request that is sent to an App Engine app when
the task is dispatched.

Using [AppEngineHttpRequest][google.cloud.tasks.v2beta3.AppEngineHttpRequest]
requires
[`appengine.applications.get`](https://cloud.google.com/appengine/docs/admin-api/access-control)
Google IAM permission for the project
and the following scope:

`https://www.googleapis.com/auth/cloud-platform`

The task will be delivered to the App Engine app which belongs to the same
project as the queue. For more information, see
[How Requests are
Routed](https://cloud.google.com/appengine/docs/standard/python/how-requests-are-routed)
and how routing is affected by
[dispatch
files](https://cloud.google.com/appengine/docs/python/config/dispatchref).
Traffic is encrypted during transport and never leaves Google datacenters.
Because this traffic is carried over a communication mechanism internal to
Google, you cannot explicitly set the protocol (for example, HTTP or HTTPS).
The request to the handler, however, will appear to have used the HTTP
protocol.

The [AppEngineRouting][google.cloud.tasks.v2beta3.AppEngineRouting] used to
construct the URL that the task is delivered to can be set at the queue-level
or task-level:

* If set,
  [app_engine_routing_override][google.cloud.tasks.v2beta3.AppEngineHttpQueue.app_engine_routing_override]
  is used for all tasks in the queue, no matter what the setting
  is for the
  [task-level
  app_engine_routing][google.cloud.tasks.v2beta3.AppEngineHttpRequest.app_engine_routing].


The `url` that the task will be sent to is:

* `url =` [host][google.cloud.tasks.v2beta3.AppEngineRouting.host] `+`
  [relative_uri][google.cloud.tasks.v2beta3.AppEngineHttpRequest.relative_uri]

Tasks can be dispatched to secure app handlers, unsecure app handlers, and
URIs restricted with
[`login:
admin`](https://cloud.google.com/appengine/docs/standard/python/config/appref).
Because tasks are not run as any user, they cannot be dispatched to URIs
restricted with
[`login:
required`](https://cloud.google.com/appengine/docs/standard/python/config/appref)
Task dispatches also do not follow redirects.

The task attempt has succeeded if the app's request handler returns an HTTP
response code in the range [`200` - `299`]. The task attempt has failed if
the app's handler returns a non-2xx response code or Cloud Tasks does
not receive response before the
[deadline][google.cloud.tasks.v2beta3.Task.dispatch_deadline]. Failed tasks
will be retried according to the [retry
configuration][google.cloud.tasks.v2beta3.Queue.retry_config]. `503` (Service
Unavailable) is considered an App Engine system error instead of an
application error and will cause Cloud Tasks' traffic congestion control to
temporarily throttle the queue's dispatches. Unlike other types of task
targets, a `429` (Too Many Requests) response from an app handler does not
cause traffic congestion control to throttle the queue.
</pre>

Protobuf type {@code google.cloud.tasks.v2beta3.AppEngineHttpRequest}
java-tasks/proto-google-cloud-tasks-v2beta3/src/main/java/com/google/cloud/tasks/v2beta3/AppEngineHttpRequest.java