To be honest, it's simply not necessary to offer separate execution environments here. All java7 and java8 jres and jdks are members of the java6 execution environment.
Also, there's no clean API in eclipse to know if one execution environment is a subset or superset of another, and so it's not really safe to be offering other execution environments in this combo.
So basically, we allow you to choose the default for the minimum execution environment the server can run on, or, if you'd like to customize it and know for sure which JRE / JDK you're using, we allow you to select any JRE / JDK that the java-6 execution environment includes. This includes all java7 and java8 installations as well as all java 6.
Thanks for that - it was plain confusing (why only one of the available exec environments ?) - the execution environments are not exactly subsets - the UI I saw you implemented is much more intuitive for eclipse users and offers the full power of exec environments
Sorry for late reply - I was sure I would be notified somehow
+ I hit my frequency limit