Fails to compile under javac 1.6.0_26

Firmament.java

package com.youdevise;

import com.youdevise.Firmament.Air.Earth;

import java.io.Serializable;

public class Firmament {
    public static class Air implements Serializable {
        public static class Earth {}
    }

    public final Earth terra = new Earth(); // this field is purely decorative
}