The bug

The translucent rendering of experience orbs is forced to happen by the game, rather than controlled by the alpha channel in the texture file, unlike other translucent objects in the game. This inhibits resource pack creators by making it impossible to give experience orbs opaque pixels, for example.

How to reproduce

1. Look at the texture file for experience orbs
2. Look at how they appear in-game

Expected results

Since experience orbs are translucent in-game, they would have translucency in their texture file.

Actual results

The texture file is completely opaque, and there is no way to make the orbs themselves opaque via resource packs.