@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 TagResourceRequestMarshaller().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, "CloudWatch");
                request.addHandlerContext(HandlerContextKey.OPERATION_NAME, "TagResource");
                request.addHandlerContext(HandlerContextKey.ADVANCED_CONFIG, advancedConfig);

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

            StaxResponseHandler<TagResourceResult> responseHandler = new StaxResponseHandler<TagResourceResult>(new TagResourceResultStaxUnmarshaller());

            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 resource. Currently, the only CloudWatch
resources that can be tagged are alarms and Contributor Insights rules.
</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 an alarm that already has tags. If you specify a new tag key
for the alarm, 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 alarm, 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 CloudWatch resource.
</p>

@param tagResourceRequest
@return Result of the TagResource operation returned by the service.
@throws InvalidParameterValueException
        The value of an input parameter is bad or out-of-range.
@throws ResourceNotFoundException
        The named resource does not exist.
@throws ConcurrentModificationException
        More than one process tried to modify a resource at the same time.
@throws InternalServiceException
        Request processing has failed due to some unknown error, exception, or failure.
@sample AmazonCloudWatch.TagResource
@see <a href="http://docs.aws.amazon.com/goto/WebAPI/monitoring-2010-08-01/TagResource" target="_top">AWS API
     Documentation</a>
aws-java-sdk-cloudwatch/src/main/java/com/amazonaws/services/cloudwatch/AmazonCloudWatchClient.java