Java.lang.Error: Unresolved compilation problems

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java. Lang. Error: Unresolved compilation problems: 
	The import com.vaadin.annotations cannot be resolved
	The import com.vaadin.annotations cannot be resolved
	The import com.vaadin.server.ThemeResource cannot be resolved
	The import com.vaadin.server.VaadinRequest cannot be resolved
	The import com.vaadin.server.VaadinServlet cannot be resolved
	The import com.vaadin.ui.Alignment cannot be resolved
	The import com.vaadin.ui.Embedded cannot be resolved
	The import com.vaadin.ui.Label cannot be resolved
	The import com.vaadin.ui.UI cannot be resolved
	The import com.vaadin.ui.VerticalLayout cannot be resolved
	The import com.vaadin.ui.themes cannot be resolved
	Theme cannot be resolved to a type