I would like to propose that regarding the header include order we follow the Google Styleguide completely. We currently have an undocumented exception in that we do not include direct headers first in the corresponding implementation files (i.e. abc.hpp -> abc.cpp).
The reasons, and examples for this are outlined in the Jira here: https://issues.apache.org/jira/browse/MESOS-2673 Please feel free to comment here on the dev-list, but also consider to comment on the Review Request directly! Thanks for your feedback, Jörg