Error building sync-endpoint-docker-swarm

I gather the github repository for sync-endpoint is in transition to 2.1.3. Currently there is an error building sync-endpoint-docker-swarm:

[INFO] -------------< org.opendatakit:sync-endpoint-docker-swarm >-------------
[INFO] Building sync-endpoint-docker-swarm 2.1.3 [4/7]
[INFO] --------------------------------[ pom ]---------------------------------
[WARNING] The POM for org.opendatakit:sync-endpoint-war:war:2.1.2 is missing, no dependency information available
[WARNING] The artifact xml-apis:xml-apis:jar:2.0.2 has been relocated to xml-apis:xml-apis:jar:1.0.b2


There are come issues around the version number right now. We do have a pending pull request to fix the problem, in the mean time you can check out the 2.1.2 tag and build from there.