private void addToCluster(Map<Object, Cluster> clusters, Object fieldValue, Document document) {
if (fieldValue == null) {
return;
}
Cluster cluster = clusters.get(fieldValue);
if (cluster == null) {
cluster = new Cluster();
cluster.addPhrases(buildClusterLabel(fieldValue));
clusters.put(fieldValue, cluster);
}
cluster.addDocuments(document);
}
