get_schema() unable to fully parse 'DescribeFeatureType' response

[soenkeliebau]

This is probably a case of "you are holding it wrong" or me misunderstanding how wfs works, but I thought I'd ask here just to be sure ..

I am trying to describe a FeatureType from a wfs service with the get_schema() method.

One example is the FeatureType "ms:gga_lk" here: https://geoportal.freiburg.de/wfs/verma_gga/verma_gga_lageklassen?request=DescribeFeatureType&service=wfs&version=2.0.0&typeNames=ms:gga_lk

This returns the following description:

<?xml version='1.0' encoding="UTF-8" ?>
<schema
   targetNamespace="http://mapserver.gis.umn.edu/mapserver"
   xmlns:ms="http://mapserver.gis.umn.edu/mapserver"
   xmlns:xsd="http://www.w3.org/2001/XMLSchema"
   xmlns="http://www.w3.org/2001/XMLSchema"
   xmlns:gml="http://www.opengis.net/gml/3.2"
   elementFormDefault="qualified" version="0.1" >

  <import namespace="http://www.opengis.net/gml/3.2"
          schemaLocation="http://schemas.opengis.net/gml/3.2.1/gml.xsd" />

  <element name="gga_lk"
           type="ms:gga_lkType"
           substitutionGroup="gml:AbstractFeature" />

  <complexType name="gga_lkType">
    <complexContent>
      <extension base="gml:AbstractFeatureType">
        <sequence>
          <element name="msGeometry" type="gml:GeometryPropertyType" minOccurs="0" maxOccurs="1"/>
          <element name="gid" minOccurs="0" type="string"/>
          <element name="objectid_1" minOccurs="0" type="string"/>
          <element name="nutzung" minOccurs="0" type="string"/>
          <element name="gfz14_iii" minOccurs="0" type="string"/>
          <element name="d_innenst" minOccurs="0" type="string"/>
          <element name="stadtteil" minOccurs="0" type="string"/>
          <element name="geschosse" minOccurs="0" type="string"/>
          <element name="jahr" minOccurs="0" type="string"/>
          <element name="brwz_nr" minOccurs="0" type="string"/>
          <element name="brw" minOccurs="0" type="string"/>
          <element name="zustand" minOccurs="0" type="string"/>
          <element name="lk_mod" minOccurs="0" type="string"/>
          <element name="lk_text" minOccurs="0" type="string"/>
          <element name="brw16sg" minOccurs="0" type="string"/>
        </sequence>
      </extension>
    </complexContent>
  </complexType>

</schema>

The code I use to retrieve the schema is this:

wfs = WebFeatureService(url='https://geoportal.freiburg.de/wfs/verma_gga/verma_gga_lageklassen', version="2.0.0")
schema = wfs.get_schema('ms:gga_lk')
print(schema)

And this outputs the following:

{'properties': {}, 'required': ['msGeometry', 'gid', 'objectid_1', 'nutzung', 'gfz14_iii', 'd_innenst', 'stadtteil', 'geschosse', 'jahr', 'brwz_nr', 'brw', 'zustand', 'lk_mod', 'lk_text', 'brw16sg'], 'geometry': 'GeometryCollection', 'geometry_column': 'msGeometry'}

This has me a bit confused because of the emtpy "properties" dict element. I would have expected to see the fields and their types listed in there, like in the example from the docs.
Am I somehow misunderstanding how all this should work together, or is the response of the wfs maybe in a non-compatible format?

I am using owslib version 0.29.2

Update:
I stepped through the code and I think this may be something to do with the namespaces declared by the webservice I am using.

The reason why the properties element is empty is because adding the fields is skipped here due to schema_key being None: https://github.com/geopython/OWSLib/blob/master/owslib/feature/schema.py#L130

schema_key is set here: https://github.com/geopython/OWSLib/blob/master/owslib/feature/schema.py#L100 while stepping though nsmap, which for my input has this value:

{
  'ms': 'http://mapserver.gis.umn.edu/mapserver', 
  'xsd': 'http://www.w3.org/2001/XMLSchema', 
  None: 'http://www.w3.org/2001/XMLSchema', 
  'gml': 'http://www.opengis.net/gml/3.2'
}

So schema_key first gets set to "xsd" and then clobbered with None in a subsequent pass, causing the code that would add the properties to get bypassed further down the line.

I am not the worlds biggest expert on xml, but the w3c validator at least seems to indicate that something is off with the schema here:

Schema Error: Cannot find preset schema for namespace: http://www.w3.org/2001/XMLSchema.

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