guava/src/com/google/common/collect/ImmutableBiMapFauxverideShim.java
@Deprecated
  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
      Function<? super T, ? extends K> keyFunction,
      Function<? super T, ? extends V> valueFunction) {
    throw new UnsupportedOperationException();
  }
@Deprecated
  public static <T, K, V> Collector<T, ?, ImmutableMap<K, V>> toImmutableMap(
      Function<? super T, ? extends K> keyFunction,
      Function<? super T, ? extends V> valueFunction) {
    throw new UnsupportedOperationException();
  }
Not supported. Use {@link ImmutableBiMap#toImmutableBiMap} instead. This method exists only to
hide {@link ImmutableMap#toImmutableMap(Function, Function)} from consumers of {@code
ImmutableBiMap}.

@throws UnsupportedOperationException always
@deprecated Use {@link ImmutableBiMap#toImmutableBiMap}.