Set up PHPStorm

In PHPStorm, use File->Open to the Elentra ME repository, then File->Open again and select the Elentra API. At this point PHPStorm will ask you if you want to open in a new window or in the same project.

Opening multiple repositories in a PHPStorm Project

By opening in current window and adding to the current project, PHPStorm will have both the Elentra ME and Elentra API codebases loaded, which will allow you to debug in the API.

This is not a required step, but it can be a convenient way to develop.