MVN Build Error #Che version: 6.0.0-M4 #68

Hello there,

I am getting below error on trying to build assembly-war-agent file:

[ERROR] Failed to execute goal on project assembly-wsagent-war: Could not resolve dependencies for project org.eclipse.che:assembly-wsagent-war:war:6.0.0-M4: Failure to find org.eclipse.che.plugin:che-plugin-mydsl-lang-server:jar:6.0.0-M4 in https://maven.codenvycorp.com/content/groups/public/ was cached in the local repository, resolution will not be reattempted until the update interval of codenvy-public-repo has elapsed or updates are forced -> [Help 1]
[ERROR]
[ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
[ERROR] Re-run Maven using the -X switch to enable full debug logging.
[ERROR]
[ERROR] For more information about the errors and possible solutions, please read the following articles:
[ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/DependencyResolutionException
[ERROR]
[ERROR] After correcting the problems, you can resume the build with the command
[ERROR] mvn -rf :assembly-wsagent-war

Do I need to change the Eclipse Che version? Is it not compatible with Maven File?
Kindly come back on it and suggest If I need to change the version or need some changes in pom.xml file of assembly.

PS: I am trying to create a plugin named mydsl. Attached is the pom file for reference.
assembly xml version.docx

Thank you!