Empty GraphML attribute is not shown with networkx

[FHantke]

Current Behavior

Currently, networkx does not show (GraphML) attributes that are empty.

Here is little example.

<?xml version='1.0' encoding='utf-8'?>
<graphml>
  <key id="d1" for="node" attr.name="foo" attr.type="string"/>
  <key id="d2" for="node" attr.name="bar" attr.type="string"/>
  <graph>
    <node id="0">
      <data key="d1">aaa</data>
      <data key="d2">bbb</data>
    </node>

    <node id="1">
      <data key="d1">ccc</data>
      <data key="d2"></data>
    </node>
  </graph>
</graphml>

If I load the file, node 0 shows both attributes while node 1 only shows the attribute foo.

G = nx.read_graphml("example.graphml")
G.nodes().get('0')
# {'foo': 'aaa', 'bar': 'bbb'}
G.nodes().get('1')
# {'foo': 'ccc'}

Expected Behavior

I would expect that node 1 shows attribute bar containing an empty string.

Environment

Python version: Python 3.11.6
NetworkX version: networkx==3.2.1

Additional context

This bug appeared during an analysis of the Brave pagegraph, see here.

[FHantke]

Thank you!