public final Set<String> getIndexColumns() {
    String colmap = conf.get(INDEXED_COLUMNS);
    if (colmap != null) {
      Set<String> cols = new HashSet<String>();
        for (String col : colmap.split(",")) {
          cols.add(col.trim());
        }
        return cols;
    }
    return EMPTY_SET;
  }
Accumulo Index Parameters for Hive tables.
accumulo-handler/src/java/org/apache/hadoop/hive/accumulo/serde/AccumuloIndexParameters.java