Specifies that the message of this queue object is enqueued ahead of the message specified by the message ID.
This method is applicable only for an enqueue operation.
Possible values include:
Any valid message identifier, specified by an array of bytes.
ORAAQ_NULL_MSGID
(Default): No message identifier specified.
Setting this property invokes enqueue with the ORAAQ_ENQ_BEFORE
option. Set this property to ORAAQ_NULL_MSGID
to place the message on top of the queue.