@SdkInternalApi
    final TagResourceResult executeTagResource(TagResourceRequest tagResourceRequest) {

        ExecutionContext executionContext = createExecutionContext(tagResourceRequest);
        AWSRequestMetrics awsRequestMetrics = executionContext.getAwsRequestMetrics();
        awsRequestMetrics.startEvent(Field.ClientExecuteTime);
        Request<TagResourceRequest> request = null;
        Response<TagResourceResult> response = null;

        try {
            awsRequestMetrics.startEvent(Field.RequestMarshallTime);
            try {
                request = new TagResourceRequestProtocolMarshaller(protocolFactory).marshall(super.beforeMarshalling(tagResourceRequest));
                // Binds the request metrics to the current request.
                request.setAWSRequestMetrics(awsRequestMetrics);
                request.addHandlerContext(HandlerContextKey.CLIENT_ENDPOINT, endpoint);
                request.addHandlerContext(HandlerContextKey.ENDPOINT_OVERRIDDEN, isEndpointOverridden());
                request.addHandlerContext(HandlerContextKey.SIGNING_REGION, getSigningRegion());
                request.addHandlerContext(HandlerContextKey.SERVICE_ID, "RUM");
                request.addHandlerContext(HandlerContextKey.OPERATION_NAME, "TagResource");
                request.addHandlerContext(HandlerContextKey.ADVANCED_CONFIG, advancedConfig);

            } finally {
                awsRequestMetrics.endEvent(Field.RequestMarshallTime);
            }

            HttpResponseHandler<AmazonWebServiceResponse<TagResourceResult>> responseHandler = protocolFactory.createResponseHandler(
                    new JsonOperationMetadata().withPayloadJson(true).withHasStreamingSuccessResponse(false), new TagResourceResultJsonUnmarshaller());
            response = invoke(request, responseHandler, executionContext);

            return response.getAwsResponse();

        } finally {

            endClientExecution(awsRequestMetrics, request, response);
        }
    }
<p>
Assigns one or more tags (key-value pairs) to the specified CloudWatch RUM resource. Currently, the only
resources that can be tagged app monitors.
</p>
<p>
Tags can help you organize and categorize your resources. You can also use them to scope user permissions by
granting a user permission to access or change only resources with certain tag values.
</p>
<p>
Tags don't have any semantic meaning to Amazon Web Services and are interpreted strictly as strings of
characters.
</p>
<p>
You can use the <code>TagResource</code> action with a resource that already has tags. If you specify a new tag
key for the resource, this tag is appended to the list of tags associated with the alarm. If you specify a tag
key that is already associated with the resource, the new tag value that you specify replaces the previous value
for that tag.
</p>
<p>
You can associate as many as 50 tags with a resource.
</p>
<p>
For more information, see <a href="https://docs.aws.amazon.com/general/latest/gr/aws_tagging.html">Tagging Amazon
Web Services resources</a>.
</p>

@param tagResourceRequest
@return Result of the TagResource operation returned by the service.
@throws ResourceNotFoundException
        Resource not found.
@throws InternalServerException
        Internal service exception.
@throws ValidationException
        One of the arguments for the request is not valid.
@sample AWSCloudWatchRUM.TagResource
@see <a href="http://docs.aws.amazon.com/goto/WebAPI/rum-2018-05-10/TagResource" target="_top">AWS API
     Documentation</a>
aws-java-sdk-cloudwatchrum/src/main/java/com/amazonaws/services/cloudwatchrum/AWSCloudWatchRUMClient.java