When I configured project with Spring, Maven and Java8, my Eclipse showed a lot of errors. I noticed mostly refusing to accept annotations:
Syntax error, annotations are only available if source level is 1.5 or greater.
Eclipse Kepler doesn’t have built in support for JDK8. So there is needed to install JDT with Java8 support.
I use Spring Tools Suite 3.5.0.RELEASE, which is still based on Eclipse Kepler (4.3.2). That is why STS needs this update.