Since SERVER-47914 and SERVER-48433 moved the LogicalClock functionality into the VectorClock, the server parameter in logical_clock.idl should be moved into a file called vector_clock.idl. The parameter name itself is maxAcceptableLogicalClockDriftSecs which, although it does mention "LogicalClock", is still sufficiently close to an accurate name that there is no need to change it (which would be a lot of effort/disruption, for no real benefit).