presto-geospatial/src/main/java/io/prestosql/plugin/geospatial/GeometryType.java/GeometryType/getObjectValue
class GeometryType:    @Override
    public Object getObjectValue(ConnectorSession session, Block block, int position)
    {
        if (block.isNull(position)) {
            return null;
        }
        Slice slice = block.getSlice(position, 0, block.getSliceLength(position));
        return deserialize(slice).asText();
    }