The singleton deployment schema file [1] is called singleton-deployment-1.0.xsd and it uses

• a dash - as a separator between name an version,
• a period . as a delimiter in the version number.

This is inconsistent with all other schema files that use an underscore _ on both places (well, there are some schemas that also use a dash - between name and version, but they are a minority). I believe that this file should be made consistent by renaming it to singleton-deployment_1_0.xsd.

[1] clustering/singleton/extension/src/main/resources/schema/singleton-deployment-1.0.xsd