FilteredKeyMultimap<K, V> prev = (FilteredKeyMultimap<K, V>) unfiltered;
      return new FilteredKeyMultimap<>(
          prev.unfiltered, Predicates.<K>and(prev.keyPredicate, keyPredicate));
    } else if (unfiltered instanceof FilteredMultimap) {
      FilteredMultimap<K, V> prev = (FilteredMultimap<K, V>) unfiltered;
      return filterFiltered(prev, Maps.<K>keyPredicateOnEntries(keyPredicate));
    } else {

import java.io.IOException;
import java.io.InvalidObjectException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
import java.lang.ref.Reference;
import java.lang.ref.ReferenceQueue;
import java.lang.ref.WeakReference;
import java.util.AbstractCollection;
import java.util.AbstractMap;
import java.util.AbstractSet;
import java.util.Collection;
import java.util.Iterator;