QVGE removes /graphml/graph/data

[agustinus-lawandy-systema]

When adding a custom graph data id=customgraphdata. With default value 'default' and actual value 'custom'
Opening and saving the file will remove that 'custom' data.

<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">

    <key id="customgraphdata" attr.name="customgraphdata" for="graph" attr.type="string">
        <default>default</default>
    </key>
	
    <graph edgedefault="undirected">
        <data key="customgraphdata">custom</data>
    </graph>
</graphml>

After saving the file <data key="customgraphdata">custom</data> is gone.

<?xml version="1.0" encoding="UTF-8"?>
<graphml xmlns="http://graphml.graphdrawing.org/xmlns" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://graphml.graphdrawing.org/xmlns http://graphml.graphdrawing.org/xmlns/1.0/graphml.xsd">
    <key id="customgraphdata" attr.name="customgraphdata" for="graph" attr.type="string">
        <default>default</default>
    </key>
    <key id="labels.policy" attr.name="labels.policy" for="graph" attr.type="integer">
        <default>0</default>
    </key>
    <key id="color" attr.name="color" for="edge" attr.type="string">
        <default>#a0a0a4</default>
    </key>
    <key id="direction" attr.name="direction" for="edge" attr.type="string">
        <default>directed</default>
    </key>
    <key id="labels.visibleIds" attr.name="labels.visibleIds" for="edge" attr.type="string">
        <default>label</default>
    </key>
    <key id="points" attr.name="points" for="edge" attr.type="string"/>
    <key id="style" attr.name="style" for="edge" attr.type="string">
        <default>solid</default>
    </key>
    <key id="weight" attr.name="weight" for="edge" attr.type="double">
        <default>1</default>
    </key>
    <key id="color" attr.name="color" for="node" attr.type="string">
        <default>#ff00ff</default>
    </key>
    <key id="labels.visibleIds" attr.name="labels.visibleIds" for="node" attr.type="string">
        <default>label</default>
    </key>
    <key id="shape" attr.name="shape" for="node" attr.type="string">
        <default>disc</default>
    </key>
    <key id="stroke.color" attr.name="stroke.color" for="node" attr.type="string">
        <default>#000000</default>
    </key>
    <key id="stroke.size" attr.name="stroke.size" for="node" attr.type="double">
        <default>1</default>
    </key>
    <key id="stroke.style" attr.name="stroke.style" for="node" attr.type="string">
        <default>solid</default>
    </key>
    <key id="x" attr.name="x" for="node" attr.type="float"/>
    <key id="y" attr.name="y" for="node" attr.type="float"/>
    <graph edgedefault="directed"/>
</graphml>