Build only subprojects in a dynamic multi-module project

For the record: to exclude compileJava task from rootProject I use the -x :compileJava
Example:

./gradlew compileJava -x :compileJava

> Task :sampleA:compileJava UP-TO-DATE
> Task :sampleA:classes
> Task :sampleB:compileJava UP-TO-DATE
> Task :sampleB:classes

If you find a better way of doing this, please let me know.