The link address of the examples code is no longer available
The examples code address in the wiki is no longer available, please change it in time
This is not a tutorial! This introduction is not intended as a tutorial, for more details about mixin implementation consult the mixin example code in the examples in the Sponge repository.
That's not the example code. This is: https://github.com/SpongePowered/SpongeCommon/tree/8c8414c352163c5a560ad6667765e682df254e17/src/example/java/org/spongepowered (SpongePowered/SpongeCommon@8c8414c352163c5a560ad6667765e682df254e17 is just a random revision I already had locally that was part of bleeding; it's probably not the latest one)
EDIT: Looks like they were removed in SpongePowered/SpongeCommon@10af5465642c3e799426659d5a807eef723be98b (found from this), so the best revision is the one before: https://github.com/SpongePowered/SpongeCommon/tree/a4fd51b8f296758e0e4ec61654cb7c14749d67b0/src/example/java/org/spongepowered
Ah I wasn't aware they'd been deleted.
They were a bit out of date anyway so I'll try and create some more up to date examples and put them on the wiki.