These non-default, "classic", functions will be deprecated in 4.3 and removed in 5.0.0.
In general, the standard ANSI SQL aggregation functions in StandardAnsiSqlAggregationFunctions should be used instead. These functions are already used by default.
AvgWithArgumentCastFunction is an alternative for databases that drop decimals when integers are averaged. This function is the default for the those dialects known to be affected by this behavior.