Support JDK 21 in ThreadUtilsTest.smoke

In JDK 21, Thread.sleep calls a "sleep0" native method. This CL fixes the
test's stack trace expectations by making it tolerant of either JDK's
stack.

PiperOrigin-RevId: 506393875
Change-Id: I653cbded4e80181348c4cd1d379cb58fdbf8f55d

src/test/java/com/google/devtools/build/lib/util/ThreadUtilsTest.java

@@ -74,10 +74,17 @@ public void handleCrash(Crash crash, CrashContext ctx) {
         .hasCauseThat()
         .hasMessageThat()
         .isEqualTo("(Wrapper exception for longest stack trace) interrupt message");
-    assertThat(reportedException.get().getCause().getStackTrace()[0].getMethodName())
-        .isEqualTo("sleep");
-    assertThat(reportedException.get().getCause().getStackTrace()[1].getMethodName())
-        .isEqualTo("recursiveMethodNoPark");
+    // The topmost method is either "sleep" or "sleep0". For example, in JDK 21, "Thread.sleep"
+    // calls a "sleep0" native method.
+    StackTraceElement[] stackTrace = reportedException.get().getCause().getStackTrace();
+    if (stackTrace[0].getMethodName().equals("sleep0")) {
+      assertThat(stackTrace[1].getMethodName()).isEqualTo("sleep");
+      assertThat(stackTrace[2].getMethodName()).isEqualTo("recursiveMethodNoPark");
+    } else {
+      assertThat(stackTrace[0].getMethodName()).isEqualTo("sleep");
+      assertThat(stackTrace[1].getMethodName()).isEqualTo("recursiveMethodNoPark");
+    }
+
     future.set(1);
     for (Thread thread : parkThreads) {
       thread.join();