MessageMetadata (Union)
union MessageMetadata = AddedParticipantsMetadata | CreatedGroupMetadata | DemotedAdminsMetadata | EditedGroupMetadata | LeftGroupMetadata | PromotedAdminsMetadata | RemovedParticipantsMetadata | TransferredOwnershipMetadata
union MessageMetadata = AddedParticipantsMetadata | CreatedGroupMetadata | DemotedAdminsMetadata | EditedGroupMetadata | LeftGroupMetadata | PromotedAdminsMetadata | RemovedParticipantsMetadata | TransferredOwnershipMetadata