public static RelDataType convert(MapTypeInfo mapType, RelDataTypeFactory dtFactory) {
    RelDataType keyType = convert(mapType.getMapKeyTypeInfo(), dtFactory);
    RelDataType valueType = convert(mapType.getMapValueTypeInfo(), dtFactory);
    return dtFactory.createMapType(keyType, valueType);
  }
******************** Convert Hive Types To Calcite Types **********************
ql/src/java/org/apache/hadoop/hive/ql/optimizer/calcite/translator/TypeConverter.java