The current version of gradle fails at startup when trying to run it with JDK 11. The following two bugs, filed against gradle, are tracking this:

https://github.com/gradle/gradle/issues/4515 -- fixed in gradle 4.7
https://github.com/gradle/gradle/issues/4860 -- fixed in gradle 4.8

But we might need a short term workaround so we can build / test with the latest JDK.