Cannot be converted to

BiKeyMap:

public interface BiKeyMap<K1, K2, V> extends Iterable<BiKeyMap.Entry<K1, K2, V>>
{
    public static class Entry<K1, K2, V>
    {
        public Entry(K1 key1, K2 key2, V value)
        {
            this.key1 = key1;
            this.key2 = key2;
            this.value = value;
        }

        protected final K1 key1;
        protected final K2 key2;
        protected final V value;

        public K1 getKey1()  { return key1;  }
        public K2 getKey2()  { return key2;  }
        public V  getValue() { return value; }
    }

    public boolean               containsKey1   (K1 key);
    public boolean               containsKey2   (K2 key);
    public boolean               containsValue  (V value);
    public V                     get            (K1 key1, K2 key2);
    public V                     put            (K1 key1, K2 key2, V value);
    public V                     remove         (K1 key1, K2 key2);
    public void                  putAll         (BiKeyMap<? extends K1, ? extends K2, ? extends V> m);
    public Set<K1>               key1Set        ();
    public Set<K2>               key2Set        ();
    public Collection<V>         values         ();
    public Set<Entry<K1, K2, V>> entrySet       ();
    public int                   size           ();
    public boolean               isEmpty        ();
    public void                  clear          ();
}

BiKeyHashMap:

public class BiKeyHashMap<K1, K2, V> implements BiKeyMap<K1, K2, V>
{
    ... Implementation ...
}

This tells me "BiKeyHashMap cannot be converted to BiKeyMap"

BiKeyMap foo = new BiKeyHashMap();

This tells me "BiKeyHashMap<Integer, Integer, Collection<Point>> cannot be converted to BiKeyMap<Integer, Integer, Collection<Point>>"

BiKeyMap<Integer, Integer, Collection<Point>> foo = new BiKeyHashMap<Integer, Integer, Collection<Point>>();