How do I look up when a method within an implemented bamboo interface is triggered?

Hi all,

I’m very new to plugin development and am having trouble finding many working tutorials for Bamboo.
If there are any sources I have missed, please do point me towards them.

I am attempting to fix bugs in an already developed plugin. Within the plugin I have a class implementing CustomVariableProviderRepository and overriding the getPlanRepositoryVariables method. This method is never called from within the plugin, so I am assuming Bamboo calls it. I would like to find out in what circumstance this method is called.

Also, how does one usually find this kind of information out?
Inspecting the Bamboo source directly?