I am using maven to create a dynamic webapp in Eclipse. I added some folders like src/test/java and src/test/resources. Also I changed the library in Java Build Path to obtain the JavaSE-1.7. It's all OK up to here.
When I tried to change the Projects Facet Dynamic Web Module something went wrong. I had change the Java to 1.7 in the same place. And it still told me, cannot change version of project facet Dynamic Web Module to 3.0.
I have changed everything that would effect the changing I think.