oldTupleType property
OldTupleType Byte1('K'): Identifies the following TupleData submessage as a key. This field is optional and is only present if the update changed data in any of the column(s) that are part of the REPLICA IDENTITY index.
Byte1('O'): Identifies the following TupleData submessage as an old tuple. This field is optional & is only present if table in which the update happened has REPLICA IDENTITY set to FULL.
The Update message may contain either a 'K' message part or an 'O' message part or neither of them, but never both of them.
Implementation
late final UpdateMessageTuple? oldTupleType;