ChatMessage throws error when used with children

[ling1726]

Environment Information

• Package version(s): (fill this out)
• Browser and OS versions: (fill this out if relevant)

Please provide a reproduction of the bug in a codepen:

Actual behavior:

When rendering ChatMessage with children, the following error will always be thrown since the header prop has a default value of {} which is inconsistent with other shorthand props for this component:

Warning: Failed prop type: Prop `author` in `ChatMessage` conflicts with props: `children`. They cannot be defined together, choose one or the other.

Repro: https://codesandbox.io/s/fluent-ui-example-forked-vg94c

Expected behavior:

No error should be thrown when rendering ChatMessage with children

Priorities and help requested:

Are you willing to submit a PR to fix? (Yes, No)

Yes

Requested priority: (Blocking, High, Normal, Low)

Normal

Products/sites affected: (if applicable)

Teams/TMP -> MessageRenderer component