When configured with "required: true", a rich text field ignores the flag and can be saved when empty.
The required property and its value are visible in the Definitions app and the JCR shows no value is saved.

Dev notes:
code field has very similar symptoms

Steps to reproduce:
1) use both codeField and richTextField  in detail/dialog
2) open detail/dialog
3) commit/save without any touch
4) add/remove some chars in code field (leave it blank)
4) commit/save

Expected:
both field should have validation error in step 3 and 5.

Actual:
only code field has validation error in step 3, no field has validation error in step 5