code: public PagedList<PoolUsageMetrics> listPoolUsageMetrics(DateTime startTime, DateTime endTime)
              throws BatchErrorException, IOException {
          return listPoolUsageMetrics(startTime, endTime, null, null);
      }
docs: Lists pool usage metrics.
  
  @param startTime
  The start time of the aggregation interval covered by this entry.
  @param endTime
  The end time of the aggregation interval for this entry.
  @return A list of {@link PoolUsageMetrics} objects.
  @throws BatchErrorException
  Exception thrown when an error response is received from the
  Batch service.
  @throws IOException
  Exception thrown when there is an error in
  serialization/deserialization of data sent to/received from the
  Batch service.