public void setPlacementGroups(java.util.Collection<PlacementGroupConfig> placementGroups) {
        if (placementGroups == null) {
            this.placementGroups = null;
            return;
        }

        this.placementGroups = new com.amazonaws.internal.SdkInternalList<PlacementGroupConfig>(placementGroups);
    }
<p>
Placement group configured for an Amazon EMR cluster.
</p>

@param placementGroups
       Placement group configured for an Amazon EMR cluster.
aws-java-sdk-emr/src/main/java/com/amazonaws/services/elasticmapreduce/model/Cluster.java