public QueryStage withSubStages(QueryStage... subStages) {
        if (this.subStages == null) {
            setSubStages(new java.util.ArrayList<QueryStage>(subStages.length));
        }
        for (QueryStage ele : subStages) {
            this.subStages.add(ele);
        }
        return this;
    }
<p>
List of sub query stages that form this stage execution plan.
</p>
<p>
<b>NOTE:</b> This method appends the values to the existing list (if any). Use
{@link #setSubStages(java.util.Collection)} or {@link #withSubStages(java.util.Collection)} if you want to
override the existing values.
</p>

@param subStages
       List of sub query stages that form this stage execution plan.
@return Returns a reference to this object so that method calls can be chained together.
aws-java-sdk-athena/src/main/java/com/amazonaws/services/athena/model/QueryStage.java