In a new project in version 8.4.0 when adding dependency in pom.xml an erro

Directory DragDropLayouts
1

In a new project in version 8.4.0 when adding dependency in pom.xml an error occurs.

GWT Module com.vaadin.v7.Vaadin7WidgetSet not found in project sources or resources. (com.vaadin: vaadin-maven-plugin: 8.4.0: compile: default: process-classes)

But in another project 8.2.0 it works.