A recent discovery when examining the metadata of my plugin I noticed that they are grouped by namespace. Checking out existing Sitecore plugins I noticed that they used one namespace for all classes in the plugin. What does this mean? Make sure all Pipelines, Entities and Components has the same namespace so the functionality of your plugin is returned together by the Commerce Engine metadata. If you're using Resharper and you don't like squiggly lines and suggestions, you can tell Resharper to ignore a folder when examining and suggesting namespace values.