Starter app won't start properly

Hi,
I have created a starter app on https://start.vaadin.com/ which contains several views offered: list, form, masterDetail. For teh implementation I chose Java.
Downloaded, unpacked and put imported the app into eclipse.
Started with
mvn jetty:run
and entered
http://localhost:8080
in the browser.

Result:
**Could not navigate to ‘’

Reason: Couldn’t find route for ‘’

Available routes:

form
list
masterdetail

This detailed message is only shown when running in development mode.**

Even if I click the one of the links (form / list / masterdetail) same message is shown, only the route and the class is different

**Could not navigate to ‘form’

Reason: Unable to create an instance of ‘com.company.project.MainView’.
. . .**

What do I do wrong?
I googled for the error message but was only able to find discussions related to running Vaadin with Spring (my app is plain Java, no Spring).

Thanks in advance!