Deprecation: #63603 - FileController and FileListController overwriteExistingFiles changed to string value 

See forge#63603

Description 

The GET/POST param to tell the FileController and FileListController whether to override a file or not switched from a bool value to a string with the possibilities of the \TYPO3\CMS\Core\Resource\DuplicationBehavior enumeration.

Impact 

Extensions still using overwriteExistingFiles = 1 will throw a deprecation warning.

Affected Installations 

All installations with extensions that use the BE upload functionality and supply the file override option.

Migration 

Change the <input name="overwriteExistingFiles" value="1"> to <input name="overwriteExistingFiles" value="replace">.