code: public UpdateThingGroupsForThingRequest withThingGroupsToAdd(String... thingGroupsToAdd) {
          if (this.thingGroupsToAdd == null) {
              setThingGroupsToAdd(new java.util.ArrayList<String>(thingGroupsToAdd.length));
          }
          for (String ele : thingGroupsToAdd) {
              this.thingGroupsToAdd.add(ele);
          }
          return this;
      }
docs: <p>
  The groups to which the thing will be added.
  </p>
  <p>
  <b>NOTE:</b> This method appends the values to the existing list (if any). Use
  {@link #setThingGroupsToAdd(java.util.Collection)} or {@link #withThingGroupsToAdd(java.util.Collection)} if you
  want to override the existing values.
  </p>
  
  @param thingGroupsToAdd
  The groups to which the thing will be added.
  @return Returns a reference to this object so that method calls can be chained together.