Add final to static-utility class
diff --git a/johnzon-mapper/src/main/java/org/apache/johnzon/mapper/ExceptionMessages.java b/johnzon-mapper/src/main/java/org/apache/johnzon/mapper/ExceptionMessages.java
index dfcecb0..858d81f 100644
--- a/johnzon-mapper/src/main/java/org/apache/johnzon/mapper/ExceptionMessages.java
+++ b/johnzon-mapper/src/main/java/org/apache/johnzon/mapper/ExceptionMessages.java
@@ -27,7 +27,7 @@
 import static javax.json.JsonValue.ValueType.STRING;
 import static javax.json.JsonValue.ValueType.TRUE;
 
-public class ExceptionMessages {
+public final class ExceptionMessages {
 
     private ExceptionMessages() {
     }