code: public AddInstanceGroupsResult withInstanceGroupIds(String... instanceGroupIds) {
          if (this.instanceGroupIds == null) {
              setInstanceGroupIds(new com.amazonaws.internal.SdkInternalList<String>(instanceGroupIds.length));
          }
          for (String ele : instanceGroupIds) {
              this.instanceGroupIds.add(ele);
          }
          return this;
      }
docs: <p>
  Instance group IDs of the newly created instance groups.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setInstanceGroupIds(java.util.Collection)} or {@link #withInstanceGroupIds(java.util.Collection)} if you
  want to override the existing values.
  </p>
  
  @param instanceGroupIds
  Instance group IDs of the newly created instance groups.
  @return Returns a reference to this object so that method calls can be chained together.