Work is underway once again to modernize and strict up the API, this time to PHP 7.2 standards. You'll probably remember the last time a strict craze happened (API 3.0.0-ALPHA7), which was very messy. This is here to give some advance warning to developers on the change set to expect, and how to prepare, to hopefully minimize the impact. What exactly is going to change? - void and ?nullable typehints will be applied everywhere it is reasonable to do so. You can guard against this in advance by adding return typehints to your code that extends or implements PM interfaces (return typehints may be made more strict by child classes). - ?nullable typehints will be applied to parameters where needed. Mostly these changes shouldn't be quite as turbulent as ALPHA7 was because this is a smaller changeset. Why typehints? Type declarations (in combination with strict types) do a range of things, including making code easier to read, exposing bugs in code more quickly (which improves maintainability) and improving safety of the API. The goal since ALPHA7 has been to expose a typed API to plugins, such that (since most plugins don't use strict types) variables will get automatically converted at the API layer to ensure sane functionality in the core while also allowing plugin devs to do whatever crazy PHP weak-type things they like. However, having said that, weak types are very scary, and I strongly recommend you try strict types for serious code. Read more about strict types and type declarations in PHP 7.x here.