presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/SpatialPartitioningStateSerializer.java/SpatialPartitioningStateSerializer/getSerializedType
class SpatialPartitioningStateSerializer:    @Override
    public Type getSerializedType()
    {
        // TODO: make serializer optional in case of non decomposable aggregation
        return VARBINARY;
    }