Error when searching tests

在链接的 JUnit 5 示例项目中展开测试节点 junit-jupiter-engine 以重现失败，然后通过 JUnit5TestFinder、CoreTestSearchEngine 和 JUnit5TestSearcher 跟踪搜索过程。完成的标准是节点展开能够在没有 Java Model Exception 的情况下完成，并发现可用的测试。

sample project: https://github.com/junit-team/junit5

try to expand the test node junit-jupiter-engine:

Java Model Exception: Error in Java Model (code 969): <anonymous #1> {key=Lorg/junit/jupiter/api/AssertThrowsAssertionsTests$7029;} [in execute() [in <lambda #1> [in assertThrowsWithExecutableThatThrowsInstanceOfAnonymousInnerClassAsUnexpectedException() [in AssertThrowsAssertionsTests [in AssertThrowsAssertionsTests.java [in org.junit.jupiter.api [in src/test/java [in junit-jupiter-engine]]]]]]]] does not exist
	at org.eclipse.jdt.internal.core.JavaElement.newNotPresentException(JavaElement.java:574)
	at org.eclipse.jdt.internal.core.JavaElement.openWhenClosed(JavaElement.java:617)
	at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:328)
	at org.eclipse.jdt.internal.core.JavaElement.getElementInfo(JavaElement.java:314)
	at org.eclipse.jdt.internal.core.Member.getFlags(Member.java:172)
	at org.eclipse.jdt.internal.junit.util.CoreTestSearchEngine.isAccessibleClass(CoreTestSearchEngine.java:64)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.internalIsTest(JUnit5TestFinder.java:251)
	at org.eclipse.jdt.internal.junit.launcher.JUnit5TestFinder.findTestsInContainer(JUnit5TestFinder.java:221)
	at com.microsoft.java.test.plugin.searcher.JUnit5TestSearcher.findTestItemsInContainer(JUnit5TestSearcher.java:130)
	at com.microsoft.java.test.plugin.util.TestSearchUtils.findTestPackagesAndTypes(TestSearchUtils.java:168)
	at com.microsoft.java.test.plugin.handler.TestDelegateCommandHandler.executeCommand(TestDelegateCommandHandler.java:56)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler$1.run(WorkspaceExecuteCommandHandler.java:230)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.jdt.ls.core.internal.handlers.WorkspaceExecuteCommandHandler.executeCommand(WorkspaceExecuteCommandHandler.java:220)
	at org.eclipse.jdt.ls.core.internal.handlers.JDTLanguageServer.lambda$4(JDTLanguageServer.java:597)
	at org.eclipse.jdt.ls.core.internal.BaseJDTLanguageServer.lambda$0(BaseJDTLanguageServer.java:87)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:646)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:483)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:373)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1182)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1655)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1622)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:165)