[Button] Disabled classes not added to the button

• The issue is present in the latest release.
• I have searched the issues of this repository and believe that this is not a duplicate.

Current Behavior 😯

“my-disabled” class not added to the Button.

Steps to Reproduce 🕹

https://codesandbox.io/s/material-ui-issue-forked-12phu?file=/src/Demo.js

<Button disabled classes={{ disabled: "my-disabled" }}>A button</Button>

[oliviertassinari]

@Boimb Either way is probably OK.

[Boimb]

@oliviertassinari , I know this issue is closed, but felt not to open a new one for my question: How can I override .Mui-contained.Mui-disabled? As far as I tried, disabled in classes does not take precedence over the “composed class”. I feel there must be a better way than adding !important to my property 😃 Thx.

[EDIT] Found the trick:

const useStyles = makeStyles(theme => ({
  contained: {
    '&$disabled': {
      backgroundColor: 'red',
    },
  },
  disabled: {}
}))

The important thing is to add the empty property disabled (can be not empty too) [/EDIT]