Neither the ssh step plugin documentation nor the SSH Step README file (_referenced as more detailed in the former doc !!) github project explains clearly the behavior controled by each arguments where it is relevant.
Specifically it is impossible to understand from the documentation how the override argument of sshGet change the step behavior.
It would be really user friendly to explain that when override is set to false not only the local file is preserved (which is awaited, but also an exception is surprisingly raised (IllegalArgumentException... which I do not really understand... but let's admit that) with an additional error message and advice .
As this exception is not really awaited, it can lead to unexpected try/catch behavior if the exact exception and its message is not checked to decide if it is a possibly awaited error (the file already exists and won't be erased) or something else more critical.
Also, the default value should be given.