Nashorn Parser JEP (https://bugs.openjdk.java.net/browse/JDK-8048176) added Parser API for ECMAScript AST. It supports ES5.1 version. This needs to be updated for ES6 version.

Note: jdk.nashorn.internal.ir classes are not exported from nashorn module. Only way new ES6 parser and IR nodes be accessible is via Nashorn parser API (jdk.nashorn.api.tree package). We need to add mirror Tree nodes and a new Visitor subclass for ES6.