diff --git a/src/main/java/com/lightstreamer/adapters/MarketDepthDemo/MarketDepthMetadataAdapter.java b/src/main/java/com/lightstreamer/adapters/MarketDepthDemo/MarketDepthMetadataAdapter.java
index 8b15d2b..df520a8 100644
--- a/src/main/java/com/lightstreamer/adapters/MarketDepthDemo/MarketDepthMetadataAdapter.java
+++ b/src/main/java/com/lightstreamer/adapters/MarketDepthDemo/MarketDepthMetadataAdapter.java
@@ -18,7 +18,6 @@
 
 import java.util.Map;
 import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.CompletionStage;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.io.File;
@@ -65,7 +64,7 @@ public boolean wantsTablesNotification(java.lang.String user) {
     private static ExecutorService messageProcessingPool = Executors.newCachedThreadPool();
 
     @Override
-    public CompletionStage<String> notifyUserMessage(String user, String session, String message) throws CreditsException, NotificationException {
+    public CompletableFuture<String> notifyUserMessage(String user, String session, String message) throws CreditsException, NotificationException {
 
         //NOTE: since the order processing is potentially blocking (in a real scenario), we have 
         //configured a dedicated ExecutorService. Moreover, to provide backpressure to the Server