import from graphml/graphson - Name cannot be in protected namespace: edge

[thjbdvlt]

hello,
i am just starting using JanusGraph and i am having trouble for loading a graph in graphml format. I have built one with python networkx (as TinkerPop doc said i may do), which i can load in TinkerPop Gremlin, but not in JanusGraph gremlin. i have this error:

gremlin> g.io("/my/file.xml).read().iterate(); 
Name cannot be in protected namespace: edge 
Type ':help' or ':h' for help. 

i have seen a question about this on stackoverflow, so i understand that JanusGraph 'reserves' this word, but what can i do? it seems like noone gave a solution that works (neither for me nor for the person who asked).
any tip? because i don't see, in networkx, anything about alternative graphml format. isn't standard?

the same happens with graphson. and i tried to load with gremlin (tinkerpop 3.7.1 ) a graph from these graphml, then write from the loaded graph a new graphml/graphson, but the problem remains: janusgraph's gremlin does not accept it.

here is what my graphml looks like:

<?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="d11" for="edge" attr.name="label" attr.type="string"/>
<key id="d10" for="node" attr.name="end_char" attr.type="string"/>
...
<key id="d0" for="node" attr.name="date" attr.type="string"/>
<graph edgedefault="undirected"><node id="0">
  <data key="d0">Dim 19 Aoû 2018 - 14:46</data>
...
<node id="284">
  <data key="d3">38</data>
  <data key="d4">3</data>
  <data key="d2">toi</data>
  <data key="d5">toi</data>
  <data key="d6">PRON</data>
  <data key="d7">Number=Sing|Person=2|PronType=Prs</data>
  <data key="d8"></data>
  <data key="d9">1379</data>
  <data key="d10">1382</data>
</node>
<edge source="0" target="1">
  <data key="d11">is_in</data>
</edge>
<edge source="0" target="2">
  <data key="d11">is_in</data>
</edge>
<edge source="0" target="3">
  <data key="d11">is_in</data>
</edge>
...
</graph></graphml>