I've noticed that given changes to Gremlin, the ReservedKeysVerificationStrategy can not be made to work properly anymore. Runtime label resolution with mergeV/E() and even property(), though the latter is probably an oversight, simply circumvents the validation and there is no reasonable way to make it work well. I suggest deprecation in 3.7.x and full removal in 4.x. If there are no objections, i'll create a JIRA.
