The default compliance level for Maven is 1.5 and every time that I update a maven project in Eclipse it sets back the compliance level from 1.6 to 1.5 which is really annoy
Another way (if you do not have already compiler plugin defined) is to set just these properties in your pom file:
1.8 1.8
Details: https://maven.apache.org/plugins/maven-compiler-plugin/examples/set-compiler-source-and-target.html