NPE when starting nuxeo-distribution-tools

I'm following the instructions from here : https://doc.nuxeo.com/display/CORG/Embedding+Nuxeo .
When trying to start the nuxeo-distribution-tools it fails with an NPE.

$ java -cp nuxeo-distribution-tools-1.4-all.jar org.nuxeo.dev.Main ./nxserver
+---------------------------------------------------------

Nuxeo Server Profile: core-5.4.1-SNAPSHOT

Home Directory: D:\sys\development\dist\nuxeo\nxserver

HTTP server at: localhost:8080

Use cache: true; Snapshot update policy: daily; offline: false +---------------------------------------------------------

Building Application ...
[ maven embedder INFO] snapshot org.nuxeo:nuxeo-ecm:5.4.1-SNAPSHOT: checking for updates from public-snapshot
-----------------------------------------------------
this realm = plexus.core
Number of imports: 0
-----------------------------------------------------
[ maven embedder WARNING] repository metadata for: 'snapshot org.nuxeo:nuxeo-ecm:5.4.1-SNAPSHOT' could not be retrieved
from repository: public-snapshot due to an error: Unsupported Protocol: 'http': Cannot find wagon which supports the req
uested protocol: http
[ maven embedder INFO] Repository 'public-snapshot' will be blacklisted
[ maven embedder WARNING] Unable to download the artifact from any repository

org.nuxeo:nuxeo-ecm:pom:5.4.1-SNAPSHOT

from the specified remote repositories:
public (http://maven.nuxeo.org/public),
central (http://repo1.maven.org/maven2),
public-snapshot (http://maven.nuxeo.org/public-snapshot)

Exception in thread "main" java.lang.NullPointerException
at org.nuxeo.build.maven.graph.Node.expand(Node.java:180)
at org.nuxeo.dev.NuxeoApp.addArtifact(NuxeoApp.java:586)
at org.nuxeo.dev.NuxeoApp.addPom(NuxeoApp.java:576)
at org.nuxeo.dev.NuxeoApp.initializeGraph(NuxeoApp.java:511)
at org.nuxeo.dev.NuxeoApp.loadConfiguration(NuxeoApp.java:298)
at org.nuxeo.dev.NuxeoApp.loadConfiguration(NuxeoApp.java:208)
at org.nuxeo.dev.NuxeoApp.build(NuxeoApp.java:192)
at org.nuxeo.dev.NuxeoApp.build(NuxeoApp.java:179)
at org.nuxeo.dev.Main.main(Main.java:125)