Running tests fails with Unrecognized option: -Xpatch:javafx.base=/home/rli/PWEs/rt/build/testing/modules/javafx.base

[Robert Lichtenberger]

According to David Hill, one has to use ea109 as base JDK for OpenJFX 
development.

I was able to setup the repository so that gradle tasks works and was 
able to build and sdk:
[rli at rlimbus rt]$ ls build/sdk/lib/
amd64  javafx-mx.jar  javafx-swt.jar  javafx.properties  jfxrt.jar

However, when I try to run some tests (e.g. in the base-module), I just 
get loads of error messages:

[rli at rlimbus base]$ gradle test
:buildSrc:generateGrammarSource UP-TO-DATE
:buildSrc:compileJava UP-TO-DATE
...
Unrecognized option: 
-Xpatch:javafx.base=/home/rli/PWEs/rt/build/testing/modules/javafx.base
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
Unrecognized option: 
-Xpatch:javafx.base=/home/rli/PWEs/rt/build/testing/modules/javafx.base
Error: Could not create the Java Virtual Machine.
Error: A fatal exception has occurred. Program will exit.
java.io.IOException: Stream closed
         at 
java.lang.ProcessBuilder$NullOutputStream.write(ProcessBuilder.java:443)
         at java.io.OutputStream.write(OutputStream.java:116)
         at 
java.io.BufferedOutputStream.flushBuffer(BufferedOutputStream.java:81)
Process 'Gradle Test Executor 2' finished with non-zero exit value 1
org.gradle.process.internal.ExecException: Process 'Gradle Test Executor 
2' finished with non-zero exit value 1
         at 
org.gradle.process.internal.DefaultExecHandle$ExecResultImpl.assertNormalExitValue(DefaultExecHandle.java:367)

I've tried to use ea126 as base JDK but that fails (of course) with:
Error occurred during initialization of VM
java.lang.ClassCastException: 
jdk.internal.loader.ClassLoaders$AppClassLoader (in module: java.base) 
cannot be cast to java.net.URLClassLoader (in module: java.base)

So how can I setup a system that will execute tests (in order to be able 
to contribute tests and patches...)?