As previously commented this array is never used.
authoreileen <emcnaughton@wikimedia.org>
Sun, 17 Feb 2019 05:18:33 +0000 (18:18 +1300)
committereileen <emcnaughton@wikimedia.org>
Sun, 17 Feb 2019 05:20:45 +0000 (18:20 +1300)
commit7668e37a857273efaa93407ab9fd70828e679186
tree2468ba24006dd6dca4a2dc901f918e9ebdc170e7
parentc9f0d440053e59f60c04d568a72e378e673e5341
As previously commented this array is never used.

I did a codebase grep on ->defaults & am pretty confident here....
CRM/Activity/Form/Search.php
CRM/Case/Form/Search.php
CRM/Contribute/Form/Search.php
CRM/Event/Form/Search.php
CRM/Grant/Form/Search.php
CRM/Member/Form/Search.php
CRM/Pledge/Form/Search.php