code: public SearchIndexResult withThingGroups(ThingGroupDocument... thingGroups) {
          if (this.thingGroups == null) {
              setThingGroups(new java.util.ArrayList<ThingGroupDocument>(thingGroups.length));
          }
          for (ThingGroupDocument ele : thingGroups) {
              this.thingGroups.add(ele);
          }
          return this;
      }
docs: <p>
  The thing groups that match the search query.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setThingGroups(java.util.Collection)} or {@link #withThingGroups(java.util.Collection)} if you want to
  override the existing values.
  </p>
  
  @param thingGroups
  The thing groups that match the search query.
  @return Returns a reference to this object so that method calls can be chained together.