code: public EnterStandbyResult withActivities(Activity... activities) {
          if (this.activities == null) {
              setActivities(new com.amazonaws.internal.SdkInternalList<Activity>(activities.length));
          }
          for (Activity ele : activities) {
              this.activities.add(ele);
          }
          return this;
      }
docs: <p>
  The activities related to moving instances into <code>Standby</code> mode.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setActivities(java.util.Collection)} or {@link #withActivities(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param activities
  The activities related to moving instances into <code>Standby</code> mode.
  @return Returns a reference to this object so that method calls can be chained together.