Document that TestExecutionListeners cannot fail test execution

Resolves #3591.

Author: marcphilipp

junit-platform-launcher/src/main/java/org/junit/platform/launcher/TestExecutionListener.java

@@ -13,6 +13,7 @@
 import static org.apiguardian.api.API.Status.STABLE;
 
 import org.apiguardian.api.API;
+import org.junit.platform.commons.util.UnrecoverableExceptions;
 import org.junit.platform.engine.TestExecutionResult;
 import org.junit.platform.engine.TestExecutionResult.Status;
 import org.junit.platform.engine.reporting.ReportEntry;
@@ -30,6 +31,12 @@
  * events are called in reverse order. Test case execution won't start before
  * all {@link #executionStarted(TestIdentifier)} calls have returned.
  *
+ * <p>If an exception is thrown by an implementation of a method of this
+ * interface, the exception will be caught and logged unless it is deemed
+ * {@linkplain UnrecoverableExceptions unrecoverable}. In consequence, a
+ * {@code TestExecutionListener} cannot cause test execution to fail or abort it
+ * early by throwing an exception.
+ *
  * <p>JUnit provides two example implementations.
  *
  * <ul>