### Concurrent Burgers

You go with your crush to get fast food, you stand in line while the cashier takes the orders from the people in front of you. 😍

<img src="/img/async/concurrent-burgers/concurrent-burgers-01.png" class="illustration">

Then it's your turn, you place your order of 2 very fancy burgers for your crush and you. 🍔🍔

import java.util.Hashtable;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Map.Entry;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentSkipListMap;
import junit.framework.Test;
import junit.framework.TestSuite;

/**
 * Generates a test suite covering the {@link Map} implementations in the {@link java.util} package.

 */
package okhttp3

import java.util.ArrayDeque
import java.util.Collections
import java.util.Deque
import java.util.concurrent.ExecutorService
import java.util.concurrent.SynchronousQueue
import java.util.concurrent.ThreadPoolExecutor
import java.util.concurrent.TimeUnit
import java.util.concurrent.locks.ReentrantLock
import okhttp3.internal.assertNotHeld
import okhttp3.internal.connection.Locks.withLock

import java.lang.ref.WeakReference
import java.net.Socket
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.ExecutorService
import java.util.concurrent.RejectedExecutionException
import java.util.concurrent.TimeUnit.MILLISECONDS
import java.util.concurrent.atomic.AtomicBoolean
import java.util.concurrent.atomic.AtomicInteger
import java.util.concurrent.locks.ReentrantLock
import okhttp3.Call
import okhttp3.Callback

import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.errorprone.annotations.concurrent.LazyInit;
import java.io.Serializable;
import java.util.Collections;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicLong;
import javax.annotation.CheckForNull;

/**

 * limitations under the License.
 */
package okhttp3.internal.concurrent

import assertk.assertThat
import assertk.assertions.isEqualTo
import java.io.Closeable
import java.util.AbstractQueue
import java.util.concurrent.BlockingQueue
import java.util.concurrent.Executors
import java.util.concurrent.TimeUnit
import java.util.logging.Logger
import kotlin.concurrent.withLock
import okhttp3.OkHttpClient

import com.google.errorprone.annotations.concurrent.LazyInit;
import java.util.Collection;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.CancellationException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Executor;
import java.util.concurrent.Future;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.ScheduledExecutorService;

import java.util.UUID;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingDeque;

import java.util.UUID;
import java.util.concurrent.BlockingDeque;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingDeque;

import java.util.Queue;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.PriorityBlockingQueue;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.TimeUnit;