chore: Improve flaky tests and add error messages

providers/flagd/src/test/java/dev/openfeature/contrib/providers/flagd/FlagdProviderSyncResourcesTest.java

@@ -79,14 +79,14 @@ void interruptingWaitingThread_isIgnored() throws InterruptedException {
     @Test
     void callingInitialize_wakesUpWaitingThread() throws InterruptedException {
         final AtomicBoolean isWaiting = new AtomicBoolean();
-        final AtomicBoolean successfulTest = new AtomicBoolean();
+        final AtomicLong waitTime = new AtomicLong(Long.MAX_VALUE);
         Thread waitingThread = new Thread(() -> {
             long start = System.currentTimeMillis();
             isWaiting.set(true);
             flagdProviderSyncResources.waitForInitialization(10000);
             long end = System.currentTimeMillis();
             long duration = end - start;
-            successfulTest.set(duration < MAX_TIME_TOLERANCE * 2);
+            waitTime.set(duration);
         });
         waitingThread.start();
 
@@ -100,7 +100,11 @@ void callingInitialize_wakesUpWaitingThread() throws InterruptedException {
 
         waitingThread.join();
 
-        Assertions.assertTrue(successfulTest.get());
+        Assertions.assertTrue(
+                waitTime.get() < MAX_TIME_TOLERANCE * 2,
+                () -> "Wakeup should be almost instant, but took " + waitTime.get()
+                        + " ms, which is more than the max of"
+                        + (MAX_TIME_TOLERANCE * 2) + " ms");
     }
 
     @Timeout(2)

providers/flagd/src/test/java/dev/openfeature/contrib/providers/flagd/e2e/State.java

@@ -9,15 +9,14 @@
 import dev.openfeature.sdk.FeatureProvider;
 import dev.openfeature.sdk.FlagEvaluationDetails;
 import dev.openfeature.sdk.MutableContext;
-import java.util.LinkedList;
-import java.util.List;
 import java.util.Optional;
+import java.util.concurrent.ConcurrentLinkedQueue;
 
 public class State {
     public ProviderType providerType;
     public Client client;
     public FeatureProvider provider;
-    public List<Event> events = new LinkedList<>();
+    public ConcurrentLinkedQueue<Event> events = new ConcurrentLinkedQueue<>();
     public Optional<Event> lastEvent;
     public FlagSteps.Flag flag;
     public MutableContext context = new MutableContext();

providers/flagd/src/test/java/dev/openfeature/contrib/providers/flagd/e2e/steps/EventSteps.java

@@ -8,7 +8,6 @@
 import io.cucumber.java.en.Given;
 import io.cucumber.java.en.Then;
 import io.cucumber.java.en.When;
-import java.util.LinkedList;
 import lombok.extern.slf4j.Slf4j;
 import org.jetbrains.annotations.NotNull;
 
@@ -19,7 +18,6 @@ public class EventSteps extends AbstractSteps {
 
     public EventSteps(State state) {
         super(state);
-        state.events = new LinkedList<>();
     }
 
     @Given("a {} event handler")