Unknown `source_server` attribute

[floriandejonckheere]

HCloud::Server.create apparently accepts a source_server attribute instead of image.

/home/florian/Code/hcloud/lib/hcloud/http.rb:52:in `post': invalid input in fields 'source_server', 'image' (HCloud::Errors::InvalidInput)
	from /home/florian/Code/hcloud/lib/hcloud/client.rb:30:in `post'
	from /home/florian/Code/hcloud/lib/hcloud/concerns/creatable.rb:12:in `create'
	from <internal:kernel>:90:in `tap'
	from /home/florian/Code/hcloud/lib/hcloud/concerns/creatable.rb:40:in `create'
	from (irb):4:in `<main>'
	from bin/console:18:in `<main>'