To resolve CMS-3183, the AmetysXSLTHelper plugin() and pluginResourceUrl(path) methods were removed. Now the XSL plugin occurrences have to be hardcoded.
This is because of internal pipelines, which override the master "plugin" request attribute. In order to be able to get the real current plugin from every pipeline step (pipeline setup, sub-pipeline, XSL rendering, and so on), we could think of a context stack. When calling a sub-request, a new context is pushed, and when it ends, the context is popped. To avoid providing a full new context every time a sub-request is invoked, a context should get its parent's variables unless explicitely specified otherwise.