Patch question

Hello,

I have a question on patch.  Coming from ORPOS world, patch is set of libraries copied under patch folder.  With Xstore , patch concetp is little bit different and want to understand clearly.  Hope some one can help /clarify.

1) Patch contents:-

Typical scenario is just one single class file /config file change - In this scenario, with base build scripts , everything underneath extension layer would  be bundled as  jar file . Example - XYZ is the client then if i check in one class then run build it will create xyz.jar ( entire customization).  How do we create patch with just only one config/class change like how Oracle release jar file for hot patch .