With JDK- 8043232, indexed selection of constructor by explicit signature works. But one has to use NativeJavaPackage for that. Because we encourage the usage of Java.type (and StaticClass) as a better way compared to older Packages and dotted access, we need to provide a way to select constructor overload via StaticClass as well.
var Color = Java.type("java.awt.Color")
var C = Color["(int,int,int)"];
var red = new C(255, 0,0);