Java 8 / Nashorn function passing class

Foo.java

import jdk.nashorn.api.scripting.NashornScriptEngine;
import jdk.nashorn.api.scripting.NashornScriptEngineFactory;

import javax.script.ScriptContext;
import java.util.function.Function;

public class Foo {
  public static void main(String[] args) throws Exception{
    System.out.println(System.getProperty("java.version"));

    NashornScriptEngine engine = (NashornScriptEngine) new NashornScriptEngineFactory().getScriptEngine();
    engine.setBindings(engine.createBindings(), ScriptContext.GLOBAL_SCOPE); //Null by default
    
    engine.eval("function proxy(a){return Java.type('Foo').bar(a);}",engine.getBindings(ScriptContext.GLOBAL_SCOPE));
    engine.eval("function withoutProxy(){return Java.type('Foo').bar(m);}",engine.getBindings(ScriptContext.ENGINE_SCOPE));
    engine.eval("function withProxy(){return proxy(m);}", engine.getBindings(ScriptContext.ENGINE_SCOPE));
    
    engine.eval("function m(a){return a;}", engine.getBindings(ScriptContext.ENGINE_SCOPE));
    
    engine.invokeFunction("withoutProxy"); //Works
    
    engine.invokeFunction("withProxy"); //ClassCastException
    
  }
  
   //Static method to call
    public static void bar(Function f){
        f.apply("-");
    }

}