Ability to use current project runtimeClasspath as "new classpath"

[sebersole]

I'd really love to just do this:

task generateDesignationsReport(type: me.champeau.gradle.japicmp.JapicmpTask) {
    ...
    newClasspath = sourceSets.main.runtimeClasspath
}

But this leads to errors about the project's (main source set) classes dir being a dir and not a jar:

   > Processing of jar file /home/sebersole/projects/hibernate/hibernate-orm/5.2/hibernate-orm/hibernate-core/target/classes/java/main failed: /home/sebersole/projects/hibernate/hibernate-orm/5.2/hibernate-orm/hibernate-core/target/classes/java/main (Is a directory)

[sebersole]

Although... it looks like this may actually be an issue in japicmp itself:

Caused by: java.io.FileNotFoundException: /home/sebersole/projects/hibernate/hibernate-orm/5.2/hibernate-orm/hibernate-core/target/classes/java/main (Is a directory)
        at japicmp.cmp.JarArchiveComparator.createListOfCtClasses(JarArchiveComparator.java:214)