code: public int convertableFrom(Type other, boolean vararg) {
          int cost = convertableFrom(other);
          if (cost < 0) { return cost; }
          
          return (vararg ? cost + 40 : cost);
      }
docs: Check if a type is convertable including support for varargs.  If varargs
  is true, then this will add 40 to the total cost such that non-varargs
  will always take precedence.
  
  @see #convertableFrom(Type)