Gradle Buildship does not respect default JRE settings


i use Eclipse running on Java 10. Since Eclipse does not support Java 10 as JRE for projects yet (but can be run by it), Java 10 is not configured/available for my Java projects:

As you can see, only Java 8 should be available to any of my projects, and Java 10 should not. However, upon import of a project that has not specified targetCompatibility (which i cannot change right now, because it is not my project), Buildship puts the Java 10 System Library onto the Build Path:

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Which of course breaks the project, because Eclipse does not support Java 10 as JRE for projects.
Expected behaviour: Buildship uses the configured default JRE (Java 8 in this case) if targetCompability is not specified.

Second image: