presto-hive/src/main/java/io/prestosql/plugin/hive/util/HiveWriteUtils.java/HiveWriteUtils/MapFieldSetter
class HiveWriteUtils:        public MapFieldSetter(SettableStructObjectInspector rowInspector, Object row, StructField field, Type keyType, Type valueType)
        {
            super(rowInspector, row, field);
            this.keyType = requireNonNull(keyType, "keyType is null");
            this.valueType = requireNonNull(valueType, "valueType is null");
        }