public List<UUID> getClusterIds() {
    List<UUID> clusterIds = new ArrayList<>();
    byte[] bytes = getAttribute(CONSUMED_CLUSTER_IDS);
    if (bytes != null) {
      ByteArrayDataInput in = ByteStreams.newDataInput(bytes);
      int numClusters = in.readInt();
      for (int i = 0; i < numClusters; i++) {
        clusterIds.add(new UUID(in.readLong(), in.readLong()));
      }
    }
    return clusterIds;
  }
Returns the set of clusterIds that have consumed the mutation
hbase-client/src/main/java/org/apache/hadoop/hbase/client/Mutation.java