Allow to not use --module-version for the Java compiler

[pzygielo]

• I hereby declare this contribution to be licenced under the Apache License Version 2.0, January 2004

[desruisseaux]

Do we need to add a new useModuleVersion plugin configuration option? Couldn't the users set the existing moduleVersion configuration option to an empty value instead if they do not want module version? It would still require a change in the code, but would avoid increasing the number of plugin configuration options.

[pzygielo]

Couldn't the users set the existing moduleVersion configuration option to an empty value instead if they do not want module version?

Let me explore that option. As long as the same goal is achieved I'm not attached to new parameter.

[pzygielo]

Do we need to add a new useModuleVersion plugin configuration option? Couldn't the users set the existing moduleVersion configuration option to an empty value

Unclear how to preserve compatibility with current default of project.version (since 3.14). Using special value not conforming to ModuleDescriptor.Version could be considered, but I don't like that idea very much.

Thus I prefer proposed solution, but I'm open to see it being solved differently.

[desruisseaux]

No special value, just allow users to specify <moduleVersion/>. The value is set to an empty or blank string, and the code just needs to test if (!moduleVersion.isEmpty()) { add the option }.

[pzygielo]

With <moduleVersion/> project.version seems to be injected. So !moduleVersion.isEmpty would always be true unless default was removed.

[pzygielo]

Then, I don't know how to differentiate the case of explicit empty or blank string set with <moduleVersion/> from the case this is not set at all, for the project.version to be used.

[desruisseaux]

It may be a question for @gnodet: we have a configuration option declared that way:

@Parameter(property = "maven.compiler.moduleVersion", defaultValue = "${project.version}")
private String moduleVersion;

Do you know if it is possible for a user to explicitly set an empty value? Apparently, using <moduleVersion/> causes Maven to fallback on defaultValue. Is there a way to said "do not use the default"? (other than adding a new useMavenVersion plugin configuration option).