I'm a bit confused since both jars "in conflict" belong to the sdk, full debug message is:
java.lang.RuntimeException: found jar hell in test classpath
at org.elasticsearch.bootstrap.BootstrapForTesting.<clinit>(BootstrapForTesting.java:92)
at org.elasticsearch.test.ESTestCase.<clinit>(ESTestCase.java:190)
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at com.carrotsearch.randomizedtesting.RandomizedRunner$1.run(RandomizedRunner.java:562)
Caused by: java.lang.IllegalStateException: jar hell!
class: jdk.packager.services.UserJvmOptionsService
jar1: /Library/Java/JavaVirtualMachines/jdk1.8.0_172.jdk/Contents/Home/lib/ant-javafx.jar
jar2: /Library/Java/JavaVirtualMachines/jdk1.8.0_172.jdk/Contents/Home/lib/packager.jar