@Override
  public String vectorExpressionParameters() {
    return getColumnParamString(0, getMapColumnNum()) + ", key: "
        + getColumnParamString(1, getIndexColumnNum());
  }
Returns value of Map.
Extends {@link VectorUDFMapIndexBaseCol}
ql/src/java/org/apache/hadoop/hive/ql/exec/vector/expressions/VectorUDFMapIndexDecimalCol.java