Fix: Cannot mark as impressed more than one message almost same time

firebase-inappmessaging/src/main/java/com/google/firebase/inappmessaging/internal/DisplayCallbacksImpl.java

@@ -42,7 +42,7 @@ public class DisplayCallbacksImpl implements FirebaseInAppMessagingDisplayCallba
   private final InAppMessage inAppMessage;
   private final String triggeringEvent;
 
-  private static boolean wasImpressed;
+  private boolean wasImpressed;
   private static final String MESSAGE_CLICK = "message click to metrics logger";
 
   @VisibleForTesting
@@ -72,6 +72,11 @@ public class DisplayCallbacksImpl implements FirebaseInAppMessagingDisplayCallba
     wasImpressed = false;
   }
 
+  @VisibleForTesting
+  boolean wasImpressed() {
+    return wasImpressed;
+  }
+
   @Override
   public Task<Void> impressionDetected() {
 

firebase-inappmessaging/src/test/java/com/google/firebase/inappmessaging/internal/DisplayCallbacksImplTest.java

@@ -258,6 +258,27 @@ public void logImpression_forVanillaCampaign_recordsImpression() {
     assertThat(wasRecorded).isTrue();
   }
 
+  @Test
+  public void logImpression_forOneMessageShouldNotAffectOtherMessages() {
+    FirebaseInAppMessagingDisplayCallbacks displayCallbacksImplOne =
+        displayCallbacksFactory.generateDisplayCallback(
+            BANNER_TEST_MESSAGE_MODEL, ANALYTICS_EVENT_NAME);
+
+    FirebaseInAppMessagingDisplayCallbacks displayCallbacksImplTwo =
+        displayCallbacksFactory.generateDisplayCallback(
+            BANNER_TEST_MESSAGE_MODEL, ANALYTICS_EVENT_NAME);
+
+    displayCallbacksImplOne.impressionDetected();
+
+    assertThat(((DisplayCallbacksImpl) displayCallbacksImplOne).wasImpressed()).isTrue();
+    assertThat(((DisplayCallbacksImpl) displayCallbacksImplTwo).wasImpressed()).isFalse();
+
+    displayCallbacksImplTwo.impressionDetected();
+
+    assertThat(((DisplayCallbacksImpl) displayCallbacksImplOne).wasImpressed()).isTrue();
+    assertThat(((DisplayCallbacksImpl) displayCallbacksImplTwo).wasImpressed()).isTrue();
+  }
+
   @Test
   public void logImpression_forTestCampaign_doesRecordImpression() {
     displayCallbacksImpl =