error with package com.google.gwt.user.client.rpc.IsSerializable in vaadin

I’m making a change from vaadin 7.2.6 to vaadin 8.3.0 but apparently the package - com.google.gwt.user.client.rpc.IsSerializable - is no longer available in vaadin 8.3.0, I could use it instead of
import com.google.gwt.user.client.rpc.IsSerializable

the one of java directly

import java.io.Serializable;

?
Thank you

That class is still present in GWT version 2.8.2 that is used in Vaadin 8.3.0, so it would be interesting to have info what error you got?

ok … this is the jar i got remove from my project vaadin-client-7.2.6.jar
vaadin-client-compiled-7.2.6.jar
vaadin-client-compiler-7.2.6.jar
vaadin-client-compiler-deps-1.1.0.jar
vaadin-push-7.2.6.jar
vaadin-sass-compiler-0.9.6.jar
vaadin-server-7.2.6.jar
vaadin-shared-7.2.6.jar
vaadin-slf4j-jdk14-1.6.1.jar
vaadin-themes-7.2.6.jar
vaadin-client-compiler-deps-1.1.0.jar
guava-16.0.1.vaadin1.jar

these are the ones that add

vaadin-client-8.3.0.jar
vaadin-client-compiled-8.3.0.jar
vaadin-client-compiler-8.3.0.jar
vaadin-push-8.3.0.jar
vaadin-sass-compiler-0.9.13.jar
vaadin-server-8.3.0.jar
vaadin-shared-8.3.0.jar
vaadin-slf4j-jdk14-1.6.1.jar
vaadin-themes-8.3.0.jar

but when i compile the source i got some errors similar to …

[javac]
C:..\MyClassImpl.java:5: package com.google.gwt.user.client.ui does not exist
[javac]
import com.google.gwt.user.client.ui.Button;
[javac]
^
[javac]
C:..\MyClassImpl.java:35: cannot find symbol
[javac]
symbol : class Button
[javac]
location: class com…engine.MyClassImpl.java
[javac]
private Button btn;
i don’t know how to fix it