Widgetset compilation error on newly created Vaadin 7.6.2 example project

Having set up a fresh Maven project from

Group Id: com.vaadin, Artifact Id: vaadin-archetype-application-example, Version 7.6.2

then performing “Compile Widgetset” by Vaadin Eclipse plugin (Eclipse GUI dropdown), I get the following warning:
Ignored 1 unit with compilation errors in first pass.
Compile with -strict or with -logLevel set to DEBUG or WARN to see all errors

When running the entirely compiled example multimodule application in Eclipse/ Jetty, the webapp runs, login works, product list shows up well in browser and editing of products seems to work fine.

My questions are:
What is the reason for the above “compilation error” to turn up (same in fresh 7.6.1 and 7.6.0 example version)?
Where in Eclipse do I have to enter compiler flags “-strict” or “-logLevel”, presumably for Java compiler (or GWT compiler?) to get more specific info on that issue?