I noticed that while we are testing the Classic Engine in the 6.0 and master Evergreen waterfalls, we do not appear to have any Classic Engine testing in the 6.3 waterfall. Was this accidental? Since SBE is still very new and large pieces of it were enabled in 6.3, we imagine that some cases could arise in which we advise customers to disable SBE in favor of the Classic Engine. In order to make such a recommendation to a customer with confidence, we need to make sure that the Classic Engine remains fully tested. Therefore, I propose adding dedicated Classic Engine build variant(s) to the 6.3 Evergreen waterfall.