diff --git a/langchain4j/src/main/java/org/bsc/langgraph4j/langchain4j/serializer/std/UserMessageSerializer.java b/langchain4j/src/main/java/org/bsc/langgraph4j/langchain4j/serializer/std/UserMessageSerializer.java
index 384b8281..3e6e7a13 100644
--- a/langchain4j/src/main/java/org/bsc/langgraph4j/langchain4j/serializer/std/UserMessageSerializer.java
+++ b/langchain4j/src/main/java/org/bsc/langgraph4j/langchain4j/serializer/std/UserMessageSerializer.java
@@ -1,19 +1,19 @@
 package org.bsc.langgraph4j.langchain4j.serializer.std;
 
 import dev.langchain4j.data.message.UserMessage;
-import org.bsc.langgraph4j.serializer.std.BaseSerializer;
+import org.bsc.langgraph4j.serializer.std.NullableObjectSerializer;
 
 import java.io.IOException;
 import java.io.ObjectInput;
 import java.io.ObjectOutput;
 
-public class UserMessageSerializer extends BaseSerializer<UserMessage> {
+public class UserMessageSerializer implements NullableObjectSerializer<UserMessage> {
     @Override
     public void write(UserMessage object, ObjectOutput out) throws IOException {
 
         if( object.hasSingleText() ) {
             out.writeUTF( object.singleText() );
-            writeUTFNullable( object.name(), out);
+            writeNullableUTF( object.name(), out);
             return;
         }
         throw new IllegalArgumentException( "Unsupported content type: " + object.type() );
@@ -22,8 +22,9 @@ public void write(UserMessage object, ObjectOutput out) throws IOException {
     @Override
     public UserMessage read(ObjectInput in) throws IOException, ClassNotFoundException {
         String text = in.readUTF();
-        return readUTFNullable(in)
-                .map( name -> UserMessage.from(name, text) ).orElseGet( () -> UserMessage.from(text) );
+        return readNullableUTF(in)
+                .map( name -> UserMessage.from(name, text) )
+                .orElseGet( () -> UserMessage.from(text) );
 
     }
 }
diff --git a/studio-jetty/src/test/java/org/bsc/langgraph4j/AgentExecutorStreamingServer.java b/studio-jetty/src/test/java/org/bsc/langgraph4j/AgentExecutorStreamingServer.java
index 6d297c87..3082073c 100644
--- a/studio-jetty/src/test/java/org/bsc/langgraph4j/AgentExecutorStreamingServer.java
+++ b/studio-jetty/src/test/java/org/bsc/langgraph4j/AgentExecutorStreamingServer.java
@@ -35,7 +35,7 @@ public static void main(String[] args) throws Exception {
         var app = new AgentExecutor().graphBuilder()
                 .chatLanguageModel(llm)
                 .objectsWithTools(listOf(new TestTool()))
-                .stateSerializer( JSONStateSerializer.of(objectMapper) )
+                .stateSerializer( AgentExecutor.Serializers.JSON.object() )
                 .build();