11gR2: ASH report has "null event" wait event

The My Oracle Support article "'Null Event' Wait Events Occurs Intermittently in ASH Report" from document ID 2102027.1 clues us into a known bug which is resolved in 12.2 and lets us know that this is a pretty insignificant issue but it is really important to know this does not mean anything so we do not freak out when we see it in the wild!