This gem is not maintained
Airbrake has release v5 of its airbrake gem, and a companion gem airbrake-ruby which addresses all of my original complaints which were the reasons for my creating this gem.
The airbrake-ruby gem should be a drop-in replacement for hydraulic_brake and I recommend users adopt it going forward.
If you're interested in documentation for a released version of hydraulic_brake, you can check out the README.md file for a prior version: https://github.com/stevecrozz/hydraulic_brake/blob/v0.2.0/README.md