MessageFilter.InboxFolder not declared with Q_ENUMS()

accessing the filter from Qt-creator is not possible since
the Q_ENUMS(StandardFolder) is missing related to

enum StandardFolder

{ InboxFolder = QMessage::InboxFolder, DraftsFolder = QMessage::DraftsFolder, OutboxFolder = QMessage::OutboxFolder, SentFolder = QMessage::SentFolder, TrashFolder = QMessage::TrashFolder }

;