Console warning when using alwaysOn ReferenceInput in Filter component

[MiMo42]

What you were expecting:
No console warnings

What happened instead:
Console warning:
Warning: React does not recognize the alwaysOn prop on a DOM element.
It hit me after set alwaysOn prop on a ReferenceInput within a Filter component.

Steps to reproduce:

• Open modified ra simple example at https://codesandbox.io/s/simple-ciybl
• Switch to Comments
• See Warning in console

Related code:
https://codesandbox.io/s/simple-ciybl

Other information:
I only had the time to do some short investigation.
It looks like alwaysOn prop is actually not sanitized, although there is a dedicated sanitizeRestProps in FilterFormInput. The alwaysOn flag is transferred to children of FilterFormInput and applied to DOM elements further down.

Environment

• React-admin version: 3.0.3
• React version: 16.12.0
• Browser: Chrome

[Kmaschta]

Reproduced, thanks!