apache calcite UDAF implementation

[张帅]

hi,
I am implementing a user-defined aggregate function, it needs input two
parameters like "AGG(column, 5)", the first is the agg column, the second
is
a number literal.
I implement it like this:
public class CalciteUDAF {
         public List init() {return new ArrayList()}
         public List add(List accumulator, Object o) {*accumulator.add(o)*}
         public Object result(List accumulator) {return xxxx}
}

I use schemaPlus.add("AGG",
AggregateFunctionImpl.create(CalciteUDAF.class)) to use it.

but how could I use the second parameter in this UDAF? could anyone give me
some advice?