* future version of {@code com.google.common.base.Supplier} will be made to <i>extend</i> {@code
 * java.util.function.Supplier}, making conversion code necessary only in one direction. At that
 * time, this interface will be officially discouraged.
 *
 * @author Harry Heymann
 * @since 2.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

   * words, the new supplier's value will be computed by retrieving the value from {@code supplier},
   * and then applying {@code function} to that value. Note that the resulting supplier will not
   * call {@code supplier} or invoke {@code function} until it is called.
   */
  public static <F extends @Nullable Object, T extends @Nullable Object> Supplier<T> compose(
      Function<? super F, T> function, Supplier<F> supplier) {

   * words, the new supplier's value will be computed by retrieving the value from {@code supplier},
   * and then applying {@code function} to that value. Note that the resulting supplier will not
   * call {@code supplier} or invoke {@code function} until it is called.
   */
  public static <F extends @Nullable Object, T extends @Nullable Object> Supplier<T> compose(
      Function<? super F, T> function, Supplier<F> supplier) {

  public void testExpiringMemoizedSupplierThreadSafe() throws Throwable {
    Function<Supplier<Boolean>, Supplier<Boolean>> memoizer =
        new Function<Supplier<Boolean>, Supplier<Boolean>>() {
          @Override
          public Supplier<Boolean> apply(Supplier<Boolean> supplier) {
            return Suppliers.memoizeWithExpiration(supplier, Long.MAX_VALUE, TimeUnit.NANOSECONDS);
          }
        };

  public void testExpiringMemoizedSupplierThreadSafe() throws Throwable {
    Function<Supplier<Boolean>, Supplier<Boolean>> memoizer =
        new Function<Supplier<Boolean>, Supplier<Boolean>>() {
          @Override
          public Supplier<Boolean> apply(Supplier<Boolean> supplier) {
            return Suppliers.memoizeWithExpiration(supplier, Long.MAX_VALUE, TimeUnit.NANOSECONDS);
          }
        };

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.base.Supplier;
import com.google.common.base.Suppliers;
import java.security.Permission;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import junit.framework.TestCase;

        public int hashCode() {
            return hash;
        }
    }

    static class CachingSupplier<T> implements Supplier<T> {
        final Supplier<T> supplier;
        volatile Object value;

        CachingSupplier(Supplier<T> supplier) {
            this.supplier = supplier;
        }

        @Override
        @SuppressWarnings({"unchecked", "checkstyle:InnerAssignment"})
        public T get() {

  public void testOr_supplier_present() {
    assertEquals("a", Optional.of("a").or(Suppliers.ofInstance("fallback")));
  }

  public void testOr_supplier_absent() {
    assertEquals("fallback", Optional.absent().or(Suppliers.ofInstance("fallback")));
  }

  public void testOr_nullSupplier_absent() {
    Supplier<Object> nullSupplier = (Supplier<Object>) Suppliers.<@Nullable Object>ofInstance(null);

      implements Function<F, T>, Serializable {

    private final Supplier<T> supplier;

    private SupplierFunction(Supplier<T> supplier) {
      this.supplier = checkNotNull(supplier);
    }

    @Override
    @ParametricNullness
    public T apply(@ParametricNullness F input) {
      return supplier.get();
    }

    @Override
    public boolean equals(@CheckForNull Object obj) {

  }

  public static <E extends @Nullable Object> SpliteratorTester<E> of(
      Supplier<Spliterator<E>> spliteratorSupplier) {
    return new SpliteratorTester<>(
        ImmutableSet.of(() -> new GeneralSpliteratorOfObject<>(spliteratorSupplier.get())));
  }

  /**
   * @since 28.1
   */
  public static SpliteratorTester<Integer> ofInt(Supplier<Spliterator.OfInt> spliteratorSupplier) {
    return new SpliteratorTester<>(