@Override
    public void addRow(Object[] value) {
      throw new RuntimeException(this.getClass().getCanonicalName() + " cannot add arrays");
    }
Sometimes, when container is empty in multi-table mapjoin, we need to add a dummy row.
This container does not normally support adding rows; this is for the dummy row.
ql/src/java/org/apache/hadoop/hive/ql/exec/persistence/HybridHashTableContainer.java