How to declare the signature of an aggregate function with variadic arguments

[shenh062326]

Currently we can add a scalar function with variadic arguments, https://facebookincubator.github.io/velox/develop/scalar-functions.html#variadic-arguments .

In some scenarios, we also need to support variadic arguments in aggregate functions. For example, we need a count(col1, col2, col3 ...) function to count the number of rows where each column is not null. Other similar variadic arguments aggregate functions include sequence_count, sequence_match, etc. But I'm not sure how to add variadic arguments aggregate functions, it will throw "Type doesn't exist: 'VARIADIC ANY'" in the following code.

std::vector<std::shared_ptr<exec::AggregateFunctionSignature>> signatures{
      exec::AggregateFunctionSignatureBuilder()
          .typeVariable("Variadic<Any>")
          .returnType("bigint")
          .intermediateType("bigint")
          .argumentType("Variadic<Any>")
          .build(),
  };

Can anyone tell me how to define a variadic arguments aggregate function or is it not supported by velox?