Recognize the .hej2 file extension
Operating System: All
Description of the feature
When a HEIF file stores a JPEG 2000 image, it should have the .hej2 file extension. Sample image here.
The latest version of GIMP can display the image if the file extension is changed to .heic or .heif. However, a simple feature would be to recognize the file with the proper .hej2 extension.
See ISO/IEC 15444-16:2021 Section 6.7.2