Fix testAfterLastInAppTimeIsDisplayedOncePerSession flakyness

* Sometimes  OneSignalPackagePrivateHelper.getShowingInAppMessageId()
can throw an NPE when running. We want to catch it so the Awaitility
will retry instead of test just failing on the first attempt.

Author: jkasten2

OneSignalSDK/unittest/src/test/java/com/test/onesignal/InAppMessageIntegrationTests.java

@@ -420,7 +420,12 @@ public void testAfterLastInAppTimeIsDisplayedOncePerSession() throws Exception {
                 .pollInterval(new Duration(10, TimeUnit.MILLISECONDS))
                 .untilAsserted(() -> {
                     assertEquals(1, OneSignalPackagePrivateHelper.getInAppMessageDisplayQueue().size());
-                    assertEquals(message1.messageId, OneSignalPackagePrivateHelper.getShowingInAppMessageId());
+                    try {
+                        assertEquals(message1.messageId, OneSignalPackagePrivateHelper.getShowingInAppMessageId());
+                    } catch (NullPointerException e) {
+                        // Awaitility won't retry if something is thrown, but will if an assert fails.
+                        fail("Should not throw");
+                    }
                 });
 
         OneSignalPackagePrivateHelper.dismissCurrentMessage();