}

  private static final class SupplierComposition<
          F extends @Nullable Object, T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    final Function<? super F, T> function;
    final Supplier<F> supplier;

    SupplierComposition(Function<? super F, T> function, Supplier<F> supplier) {
      this.function = checkNotNull(function);
      this.supplier = checkNotNull(supplier);
    }

  }

  private static final class SupplierComposition<
          F extends @Nullable Object, T extends @Nullable Object>
      implements Supplier<T>, Serializable {
    final Function<? super F, T> function;
    final Supplier<F> supplier;

    SupplierComposition(Function<? super F, T> function, Supplier<F> supplier) {
      this.function = checkNotNull(function);
      this.supplier = checkNotNull(supplier);
    }

        .addEqualityGroup(
            Suppliers.compose(Functions.constant(1), Suppliers.ofInstance("foo")),
            Suppliers.compose(Functions.constant(1), Suppliers.ofInstance("foo")))
        .addEqualityGroup(Suppliers.compose(Functions.constant(2), Suppliers.ofInstance("foo")))
        .addEqualityGroup(Suppliers.compose(Functions.constant(1), Suppliers.ofInstance("bar")))
        .testEquals();
  }

/**
 * Legacy version of {@link java.util.function.Supplier java.util.function.Supplier}. Semantically,
 * this could be a factory, generator, builder, closure, or something else entirely. No guarantees
 * are implied by this interface.
 *
 * <p>The {@link Suppliers} class provides common suppliers and related utilities.
 *
 * <p>As this interface extends {@code java.util.function.Supplier}, an instance of this type can be

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 com.google.common.util.concurrent.TestExceptions.SomeCheckedException;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import junit.framework.TestCase;

 * 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
public interface Supplier<T extends @Nullable Object> {

    builder.weigher(constantWeigher(42)).build(CacheLoader.from(Suppliers.ofInstance(null)));
  }

  @SuppressWarnings("ReturnValueIgnored")
  public void testMaximumWeight_withoutWeigher() {
    CacheBuilder<Object, Object> builder = CacheBuilder.from(parse("maximumWeight=9000"));
    assertThrows(
        IllegalStateException.class,
        () -> builder.build(CacheLoader.from(Suppliers.ofInstance(null))));
  }

    builder.weigher(constantWeigher(42)).build(CacheLoader.from(Suppliers.ofInstance(null)));
  }

  @SuppressWarnings("ReturnValueIgnored")
  public void testMaximumWeight_withoutWeigher() {
    CacheBuilder<Object, Object> builder = CacheBuilder.from(parse("maximumWeight=9000"));
    assertThrows(
        IllegalStateException.class,
        () -> builder.build(CacheLoader.from(Suppliers.ofInstance(null))));
  }

final class MultiInputStream extends InputStream {

  private final Iterator<? extends ByteSource> it;
  private @Nullable InputStream in;

  /**
   * Creates a new instance.
   *
   * @param it an iterator of I/O suppliers that will provide each substream
   */
  public MultiInputStream(Iterator<? extends ByteSource> it) throws IOException {
    this.it = checkNotNull(it);
    advance();
  }

  @Override

  }

  Logger get() {
    /*
     * We use double-checked locking. We could the try racy single-check idiom, but that would
     * depend on Logger to not contain mutable state.
     *
     * We could use Suppliers.memoizingSupplier here, but I micro-optimized to this implementation
     * to avoid the extra class for the lambda (and maybe more for memoizingSupplier itself) and the
     * indirection.
     *