temp Remove content-length from expected HEAD headers
Add /groups validation
Add POST /groups validations
Add GET /groups/:id validations
Add HEAD /groups validations
Add GET /groups validations
Add PUT /groups/:id validations
Add DELETE /groups/:id validations
Add OPTIONS /groups validation
Add GET /groups/:id validations when group not found
Add PUT /groups/:id validations when group not found
Add DELETE /groups/:id validations when not found