The value of 'xcmHrDevAlertIndex' for the most recently-added
alert (critical or non-critical) in the alert table. This value
only reflects the most recently added alert; if the alert is
subsequently cleared, the value of 'xcmHrDevAlertAllEvents'
SHALL NOT be changed as a result. Compliant implementations
SHALL report zero if no alerts have been added to the table.
A management tool may use the fact that this value has not
changed to avoid checking for new alerts.
Note that the value of this object will 'wrap' when the first
alert is added to the table after 'xcmHrDevAlertIndex'
has reached 2**32 - 1 and 'wrapped' to 1.