Main class name of manifest is incorrect when using Application plugin with JPMS

[mpe85]

ShadowJar produces a Jar with an incorrect Main-Class entry in the manifest file. This happens when you apply the Application plugin and you have a java 9 module.

Shadow Version

5.0.0

Gradle Version

5.3.1

Expected Behavior

I applied the application plugin in a project that uses the java 9 module system. Therefore the main class name must be specified including the module name, otherwise the application plugin prints a warning (e.g. when I try to run the 'run' task):

application {
  mainClassName = "$moduleName/x.y.Z"
}

I would expect ShadowJar to put the main class name without the module name into the manifest: Main-Class: x.y.Z

Actual Behavior

ShadowJar puts the main class attribute including the module name into the manifest: Main-Class: a.b.c/x.y.Z

When trying to execute the fat jar using java -jar xxx.jar it fails with an error because it does not find the class inside the package a.b.c.x.y (which of course does not exist)

It's not possible to override the manifest entry manually using manifest.attributes["Main-Class"] = x.y.Z No matter what I specify here, ShadowJar always uses application.mainClassName

Gradle Build Script(s)

See above

Content of Shadow JAR (jar tf <jar file> - post link to GIST if too long)

[chrismaster]

Any news on this one?

It seems the application (or here jlink) plugin overrides the MainClassName attribute from the jar plugin.

I think a.b.c.x.y is only a terminal problem. In the manifest of the jar should be a.b.c/x.y.Z

Try java -cp shadowJar.jar x.y.Z

How to set the MainClassName from shadow plugin?

So from the docs jar { manifest { attributes 'Main-Class': 'my.main.ClassName'
} } wont work

[mpe85]

@johnrengelman Could you please provide any information about this?

[johnrengelman]

When using JPMS, there must be a different task generating the Manifest file (other than the normal Jar task). ShadowJar by default, inherits it’s config from Jar, so you’ll need to change that. https://imperceptiblethoughts.com/shadow/configuration/#configuring-the-jar-manifest