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;
    }
<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.
aws-java-sdk-iot/src/main/java/com/amazonaws/services/iot/model/UpdateThingGroupsForThingRequest.java