Use interface instead of implementation (#10073)

1 files changed, 2 insertions, 1 deletions

diff --git a/server/src/main/java/com/vaadin/ui/Flash.java b/server/src/main/java/com/vaadin/ui/Flash.java
index ced6d0bbad..affda1a372 100644
--- a/server/src/main/java/com/vaadin/ui/Flash.java
+++ b/server/src/main/java/com/vaadin/ui/Flash.java
@@ -18,6 +18,7 @@ package com.vaadin.ui;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import org.jsoup.nodes.Element;
@@ -238,7 +239,7 @@ public class Flash extends AbstractEmbedded {
         super.writeDesign(design, designContext);
 
         // Parameters, in alphabetic order
-        ArrayList<String> paramNames = new ArrayList<>();
+        List<String> paramNames = new ArrayList<>();
         for (String param : getParameterNames()) {
             paramNames.add(param);
         }