Minimal test case reproducing Genson error

TestGenson.java

package test;

import com.owlike.genson.Genson;
import com.owlike.genson.GensonBuilder;

import java.util.HashMap;
import java.util.Map;

public class TestGenson {

    static public void main(String[] args) 
    {
        Genson genson = new GensonBuilder().setSkipNull(true).create();

        Map<String, String> m = new HashMap<String,String>();
        m.put("abcde", "normal");
        m.put("fg\"hi", "with quote");
        m.put("ij\\klmn", "with slash");

        System.out.println("map='" + m + "'");
        System.out.println("genson='" + genson.serialize(m) + "'");
    }
}