Hoppers stick to Slime Blocks

Not sure if this is intended behaviour, I always assumed that Hoppers were one of the blocks that didn't stick to Slime Blocks, but apparently they do.

1/ create a basic Slime Block engine
2/ attach Hoppers to Slime Blocks
3/ turn engine on.

slime blocks and hoppers

If this is intended behaviour then I'm sorry for the inconvenience of the post.