* for (Challenge challenge : response.challenges()) {
 *   // If this is preemptive auth, use a preemptive credential.
 *   if (challenge.scheme().equalsIgnoreCase("OkHttp-Preemptive")) {
 *     return response.request().newBuilder()
 *         .header("Proxy-Authorization", "secret")
 *         .build();
 *   }
 * }
 * return null; // Didn't find a preemptive auth scheme.
 * ```
 *
 * ## Reactive Authentication
 *

import static com.google.common.primitives.UnsignedLongs.max;
import static com.google.common.primitives.UnsignedLongs.min;
import static com.google.common.truth.Truth.assertThat;
import static java.math.BigInteger.ONE;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

import static com.google.common.collect.Multisets.sum;
import static com.google.common.collect.Multisets.union;
import static com.google.common.collect.Multisets.unmodifiableMultiset;
import static com.google.common.truth.Truth.assertThat;
import static java.util.Arrays.asList;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

 * or implied. See the License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static com.google.common.util.concurrent.ClassPathUtil.parseJavaClassPath;
import static com.google.common.util.concurrent.Futures.getChecked;

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.util.concurrent;

import static com.google.common.truth.Truth.assertThat;
import static java.util.concurrent.Executors.newSingleThreadExecutor;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static org.junit.Assert.assertThrows;

import static com.google.common.io.TestOption.OPEN_THROWS;
import static com.google.common.io.TestOption.READ_THROWS;
import static com.google.common.io.TestOption.WRITE_THROWS;
import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableSet;
import com.google.common.collect.Iterables;

import static com.google.common.base.Throwables.propagateIfPossible;
import static com.google.common.base.Throwables.throwIfInstanceOf;
import static com.google.common.base.Throwables.throwIfUnchecked;
import static com.google.common.truth.Truth.assertThat;
import static java.util.regex.Pattern.quote;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

import static com.google.common.testing.SerializableTester.reserialize;
import static com.google.common.testing.SerializableTester.reserializeAndAssert;
import static com.google.common.truth.Truth.assertThat;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;

## Description of `xl.meta`

`xl.meta` is a new self describing backend format used by MinIO to support AWS S3 compatible versioning.
This file is the source of truth for each `version` at rest. `xl.meta` is a msgpack file serialized from a
well defined data structure. To understand `xl.meta` here are the few things to start with

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.collect;

import static com.google.common.truth.Truth.assertThat;
import static java.util.Collections.singleton;
import static org.junit.Assert.assertThrows;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;