Deprecation: #87200 - EmailFinisher FORMAT_* constants

See Issue #87200

Description

The constants EmailFinisher::FORMAT_PLAINTEXT and EmailFinisher::FORMAT_HTML have been deprecated and will be removed in TYPO3 11.0.

Impact

Accessing these constants will lead to a fatal error in TYPO3 11.0.

Affected Installations

All installations which use EXT:form and directly access these constants.

Migration

Do not use these constants anymore.