Available from version 1.6.0
Runs for every Special page that extends the QueryPage class (fired when including the file QueryPage.php). It is only useful in maintenance/updateSpecialPages.php and in QueryPage Api.
Define function:
public static function onwgQueryPages( &$wgQueryPages ) { ... }
Attach hook: In extension.json:
	"Hooks": {
		"wgQueryPages": "MediaWiki\\Extension\\MyExtension\\Hooks::onwgQueryPages"
Called from: File(s): specialpage/QueryPage.php
Interface: WgQueryPagesHook.php

For more information about attaching hooks, see Manual:Hooks .
For examples of extensions using this hook, see Category:wgQueryPages extensions.

Details edit

$wgQueryPages is an array of 2-element arrays. The first element of each array is the class name of the query page. The second element of each array is the name registered in your special page's constructor.