fixup: simplify EventProvider.attach to single CAS

per chrfwow's review suggestion. The previous CAS loop existed to
support a no-op-same-onEmit branch which is unreachable in practice:
attach() is package-private (not part of the public API), and the
sole production caller (OpenFeatureAPI.attachEventProvider) always
passes a fresh method-reference. Drops the now-orphaned
doesNotThrowWhenOnEmitSame test.

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

Author: toddbaert

src/main/java/dev/openfeature/sdk/EventProvider.java

@@ -49,7 +49,6 @@ private static final class Attachment {
 
     /**
      * "Attach" this EventProvider to an SDK, which allows events to propagate from this provider.
-     * No-op if the same onEmit is already attached.
      *
      * @param onEmit the function to run when a provider emits events.
      * @param lock   the API instance's read/write lock for thread safety.
@@ -59,16 +58,9 @@ void attach(
             TriConsumer<EventProvider, ProviderEvent, ProviderEventDetails> onEmit,
             AutoCloseableReentrantReadWriteLock lock) {
         Attachment newAttachment = new Attachment(onEmit, lock);
-        while (true) {
-            Attachment existing = this.attachment.get();
-            if (existing != null && existing.onEmit != onEmit) {
-                // if we are trying to attach this provider to a different onEmit, something has gone wrong
-                throw new IllegalStateException(
-                        "Provider " + this.getMetadata().getName() + " is already attached.");
-            }
-            if (this.attachment.compareAndSet(existing, newAttachment)) {
-                return;
-            }
+        if (!this.attachment.compareAndSet(null, newAttachment)) {
+            throw new IllegalStateException(
+                    "Provider " + this.getMetadata().getName() + " is already attached.");
         }
     }
 

src/test/java/dev/openfeature/sdk/EventProviderTest.java

@@ -82,16 +82,6 @@ void throwsWhenOnEmitDifferent() {
         assertThrows(IllegalStateException.class, () -> eventProvider.attach(onEmit2, lock));
     }
 
-    @Test
-    @DisplayName("should not throw if second same onEmit attached")
-    void doesNotThrowWhenOnEmitSame() {
-        TriConsumer<EventProvider, ProviderEvent, ProviderEventDetails> onEmit1 = mockOnEmit();
-        TriConsumer<EventProvider, ProviderEvent, ProviderEventDetails> onEmit2 = onEmit1;
-        eventProvider.attach(onEmit1, new AutoCloseableReentrantReadWriteLock());
-        eventProvider.attach(
-                onEmit2, new AutoCloseableReentrantReadWriteLock()); // should not throw, same instance. noop
-    }
-
     @Test
     @Timeout(value = 2, threadMode = Timeout.ThreadMode.SEPARATE_THREAD)
     @DisplayName("emit should acquire read lock when attached")