Hello World,

m2e 1.6.2 ( RC1 for Mars has been released. It notably fixes a regression introduced in 1.6.1 that broke the groovy configurator. See the changelog here [1]. It can be installed from [2]. 3rd party configurator providers are *strongly* encouraged to check 1.6.2 works for them.
Unless new blocking issues are found for m2e, it will most likely be released as-is next week.

m2e 1.7.0 ( M1 for Neon includes all the fixes from 1.6.2 plus initial Java 9 support [3]. It can be installed from [4].
Java 9 beta support for Eclipse must be installed from the Marketplace[5].
Please note m2e 1.7.0 now requires JDK 8 minimum to run. 



[1] https://bugs.eclipse.org/bugs/buglist.cgi?bug_status=RESOLVED&bug_status=VERIFIED&bug_status=CLOSED&list_id=12449669&product=m2e&query_format=advanced&resolution=FIXED&target_milestone=1.6.2%2FMars%20RC1
[2] http://download.eclipse.org/technology/m2e/milestones/1.6/
[3] https://bugs.eclipse.org/bugs/buglist.cgi?bug_status=RESOLVED&bug_status=VERIFIED&bug_status=CLOSED&list_id=12449669&product=m2e&query_format=advanced&resolution=FIXED&target_milestone=1.7.0%2FNeon%20M1
[4] http://download.eclipse.org/technology/m2e/milestones/1.7/
[5] https://www.eclipse.org/mars/noteworthy/#_java_9_beta

"Have you tried turning it off and on again" - The IT Crowd
And if that fails, then http://goo.gl/tnBgH5