Collects the metrics at the end of a request/response cycle, transforms
the metric data points into a cloud watch metric datum representation,
and then adds it to a memory queue so it will get summarized into the
necessary statistics and uploaded to Amazon CloudWatch.
Returns a instance of the Amazon CloudWatch request metric collector either by
starting up a new one or returning an existing one if it's already
started; null if any failure.
Returns a request type specific metrics for
AWSRequestMetrics.Field.ClientExecuteTime which is special in the sense that it
makes a more accurate measurement by taking the TimingInfo at the
root into account.
Returns a list of metric datum for the metrics collected for the given
request/response, or null if this transformer does not recognize the
specific input metric type.