Function<@Nullable Object, Integer> function = Functions.forSupplier(supplier);

    assertEquals(1, (int) function.apply(null));
    assertEquals(2, (int) function.apply("foo"));

    new EqualsTester()
        .addEqualityGroup(function, Functions.forSupplier(supplier))
        .addEqualityGroup(Functions.forSupplier(new CountingSupplier()))
        .addEqualityGroup(Functions.forSupplier(Suppliers.ofInstance(12)))

    Function<@Nullable Object, Integer> function = Functions.forSupplier(supplier);

    assertEquals(1, (int) function.apply(null));
    assertEquals(2, (int) function.apply("foo"));

    new EqualsTester()
        .addEqualityGroup(function, Functions.forSupplier(supplier))
        .addEqualityGroup(Functions.forSupplier(new CountingSupplier()))
        .addEqualityGroup(Functions.forSupplier(Suppliers.ofInstance(12)))

   *
   * @since 10.0
   */
  public static <F extends @Nullable Object, T extends @Nullable Object> Function<F, T> forSupplier(
      Supplier<T> supplier) {
    return new SupplierFunction<>(supplier);
  }

  /**
   * @see Functions#forSupplier
   */
  private static final class SupplierFunction<
          F extends @Nullable Object, T extends @Nullable Object>