Is your feature request related to a problem? Please describe.
I am trying to implement TestLifecycleListener in which I need to identify from the TestResult object to which test it corresponds. JUnit Platform uses TestIdentifer for uniquely identifying the tests. Hence I would like to be able to navigate from TestResult to TestIdentifier.

Describe the solution you'd like
Add a String field to TestResult to store the value obtained by invoking toString() on org.junit.platform.engine.UniqueId obtained from the TestIdentifier instance.
TestResult has a field testCaseId which doesn't seem to be used for other purposes at the moment. Hence I believe we could make of that field for this purpose. Please suggest.