def METHOD_NAME(tmpdir, driver, extension):
    """
    In GDAL 2.2 the behaviour of OGR_F_IsFieldSet slightly changed. Some drivers
    (e.g. GeoJSON) also require fields to be explicitly set to null.
    See GH #460.
    """
    meta = {
        "driver": driver,
        "schema": {"geometry": "Point", "properties": {"RETURN_P": "str"}},
    }
    filename = os.path.join(str(tmpdir), "test_null." + extension)
    with fiona.open(filename, "w", **meta) as dst:
        g = {"coordinates": [1.0, 2.0], "type": "Point"}
        feature = Feature.from_dict(**{"geometry": g, "properties": {"RETURN_P": None}})
        dst.write(feature)
    with fiona.open(filename, "r") as src:
        feature = next(iter(src))
        assert feature.properties["RETURN_P"] is None