Pull in 3.2.4 version of SseBroadcasterImpl

This avoids a change made in 3.2.5 or 3.2.6 that breaks Liberty's impl.
The change forces users to use the CXF SseEventSinkImpl rather than a
custom impl (like our LibertySseEventSinkImpl).  At some point, we
should start to use the CXF impl, but for now, we'll use the 3.2.4
version of SseBroadcasterImpl so as to continue working with our
existing LibertySseEventSinkImpl.

Author: andymc12

dev/com.ibm.ws.org.apache.cxf.cxf.rt.rs.sse.3.2/src/org/apache/cxf/jaxrs/sse/SseBroadcasterImpl.java

@@ -0,0 +1,80 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.cxf.jaxrs.sse;
+
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Set;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CompletionStage;
+import java.util.concurrent.CopyOnWriteArraySet;
+import java.util.function.BiConsumer;
+import java.util.function.Consumer;
+
+import javax.ws.rs.sse.OutboundSseEvent;
+import javax.ws.rs.sse.SseBroadcaster;
+import javax.ws.rs.sse.SseEventSink;
+
+public class SseBroadcasterImpl implements SseBroadcaster {
+    private final Set<SseEventSink> subscribers = new CopyOnWriteArraySet<>();
+
+    private final Set<Consumer<SseEventSink>> closers =
+            new CopyOnWriteArraySet<>();
+
+    private final Set<BiConsumer<SseEventSink, Throwable>> exceptioners =
+            new CopyOnWriteArraySet<>();
+
+    @Override
+    public void register(SseEventSink sink) {
+        subscribers.add(sink);
+    }
+
+    @Override
+    public CompletionStage<?> broadcast(OutboundSseEvent event) {
+        final Collection<CompletableFuture<?>> futures = new ArrayList<>();
+        
+        for (SseEventSink sink: subscribers) {
+            try {
+                futures.add(sink.send(event).toCompletableFuture());
+            } catch (final Exception ex) {
+                exceptioners.forEach(exceptioner -> exceptioner.accept(sink, ex));
+            }
+        }
+        
+        return CompletableFuture.allOf(futures.toArray(new CompletableFuture[futures.size()]));
+    }
+
+    @Override
+    public void onClose(Consumer<SseEventSink> subscriber) {
+        closers.add(subscriber);
+    }
+
+    @Override
+    public void onError(BiConsumer<SseEventSink, Throwable> exceptioner) {
+        exceptioners.add(exceptioner);
+    }
+
+    @Override
+    public void close() {
+        subscribers.forEach(subscriber -> {
+            subscriber.close();
+            closers.forEach(closer -> closer.accept(subscriber));
+        });
+    }
+}