Search-Mailbox cmdlet has no -SearchDumpsterOnly parameter

I keep seeing references to a '-SearchDumpsterOnly' parameter that can be used with the Search-Mailbox cmdlet. I've even seen it documented on Technet. However, any time I attempt to use it in the Exchange Management Shell, I get the following output:

[PS] C:\Windows\System32>Search-Mailbox <email> -searchDumpsterOnly -TargetMailbox "Discovery Search Mailbox" -TargetFolder LitigationHold -LogLevel Full

A positional parameter cannot be found that accepts argument '-searchDumpsterOnly'.
 + CategoryInfo : InvalidArgument: (:) [Search-Mailbox], ParameterBindingException
 + FullyQualifiedErrorId : PositionalParameterNotFound,Search-Mailbox

Now, it all works fine if I use '-SearchDumpster' instead, except that it include all other folders as well (as it should). Get-Help Search-Mailbox -Full shows no listing for '-SearchDumpsterOnly'

Is there a prerequisite patch to get this this parameter?