code: public FleetAttributes withMetricGroups(String... metricGroups) {
          if (this.metricGroups == null) {
              setMetricGroups(new java.util.ArrayList<String>(metricGroups.length));
          }
          for (String ele : metricGroups) {
              this.metricGroups.add(ele);
          }
          return this;
      }
docs: <p>
  Names of metric groups that this fleet is included in. In Amazon CloudWatch, you can view metrics for an
  individual fleet or aggregated metrics for fleets that are in a fleet metric group. A fleet can be included in
  only one metric group at a time.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setMetricGroups(java.util.Collection)} or {@link #withMetricGroups(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param metricGroups
  Names of metric groups that this fleet is included in. In Amazon CloudWatch, you can view metrics for an
  individual fleet or aggregated metrics for fleets that are in a fleet metric group. A fleet can be
  included in only one metric group at a time.
  @return Returns a reference to this object so that method calls can be chained together.