code: public void setGroupings(java.util.Collection<String> groupings) {
          if (groupings == null) {
              this.groupings = null;
              return;
          }
  
          this.groupings = new java.util.ArrayList<String>(groupings);
      }
docs: <p>
  The grouping applied to the metrics returned. For example, when results are grouped by queueId, the metrics
  returned are grouped by queue. The values returned apply to the metrics for each queue rather than aggregated for
  all queues.
  </p>
  <p>
  The current version supports grouping by Queue
  </p>
  <p>
  If no <code>Grouping</code> is included in the request, a summary of <code>HistoricalMetrics</code> for all
  queues is returned.
  </p>
  
  @param groupings
  The grouping applied to the metrics returned. For example, when results are grouped by queueId, the
  metrics returned are grouped by queue. The values returned apply to the metrics for each queue rather than
  aggregated for all queues.</p>
  <p>
  The current version supports grouping by Queue
  </p>
  <p>
  If no <code>Grouping</code> is included in the request, a summary of <code>HistoricalMetrics</code> for
  all queues is returned.
  @see Grouping