player skin changed

[chrissiOnAir]

hi, this may be a strange question, but i couldn't find an answer for it yet:

 

Today i was working on Eclipse with version 10.12 (not the 10.12.1) and i tested some times running the client.

Suddenly only for one time my player skin had changed! I have no screenshot (blame myself), but it was kind of black/orange with a red eye.

 

Have i been hacked somehow or is this kind of a build in forge-feature?

[jabelar]

If you don't supply --username Minecraft picks a random "player****" as your name.

 

Where do you specify this?  In the arguments of the Eclipse run configuration?