Vaadin-Sample Problem

Hello,
I’m using until now older version from vaadin with Ivy in Hybrid. Just now I want change to newly Version/System with Maven. I’m trying start Vaadin-sample but I take Error:

[INFO]

[INFO]
Building myvaadintest 1.0-SNAPSHOT
[INFO]

[INFO]

[INFO]
— vaadin-maven-plugin:7.7.3:update-widgetset (default-cli) @ myvaadintest —
[WARNING]
GWT plugin is configured to detect modules, but none were found.
[INFO]
No widgetsets found - generating AppWidgetset if necessary.
[INFO]
Updating widgetset AppWidgetset
[INFO]
Adding resource directory to command classpath: C:\Users\m\workspace\neon1\myvaadintest\src\main\resources
[INFO]
Adding resource directory to command classpath: C:\Users\m\workspace\neon1\myvaadintest\target\generated-resources\gwt
[INFO]
Using com.vaadin:vaadin-client version 7.7.3
[INFO]
Using com.vaadin:vaadin-client-compiler version 7.7.3
[INFO]
Widgetsets found from classpath:
[INFO]
com.vaadin.DefaultWidgetSet in jar:file:C:/Users/m/.m2/repository/com/vaadin/vaadin-client/7.7.3/vaadin-client-7.7.3.jar!/
[INFO]
Addon styles found from classpath:
[INFO]

[INFO]
Search took 11ms
[INFO]

[INFO]
— vaadin-maven-plugin:7.7.3:compile (default-cli) @ myvaadintest —
[INFO]
auto discovered modules [AppWidgetset]

[INFO]
Using com.vaadin:vaadin-client version 7.7.3
[INFO]
Using com.vaadin:vaadin-client-compiler version 7.7.3
[INFO]

[INFO]
BUILD FAILURE
[INFO]

[INFO]
Total time: 2.358 s
[INFO]
Finished at: 2016-10-20T11:48:59+02:00
[INFO]
Final Memory: 14M/159M
[INFO]

[ERROR]
Failed to execute goal com.vaadin:vaadin-maven-plugin:7.7.3:compile (default-cli) on project myvaadintest: GWT Module elemental.Json not found in project sources or resources. → [Help 1]

[ERROR]

someone a idea ?

And now I don’t see more in generated source *.gwt.xml file ? Is this removed ?

Thanks a lot