Available from version 1.38.0 (Gerrit change 724228)
Add extra pages to the list of pages to export.
Define function:
public static function onSpecialExportGetExtraPages( array $inputPages, array &$extraPages ) { ... }
Attach hook: In extension.json:
	"Hooks": {
		"SpecialExportGetExtraPages": "MediaWiki\\Extension\\MyExtension\\Hooks::onSpecialExportGetExtraPages"
Called from: File(s): specials/SpecialExport.php
Function(s): getExtraPages
Interface: SpecialExportGetExtraPagesHook.php

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