void cleanUp() {
    if (threadStarted) {
      return;
    }

    Reference<?> reference;
    while ((reference = queue.poll()) != null) {
      /*
       * This is for the benefit of phantom references. Weak and soft references will have already
       * been cleared by this point.
       */
      reference.clear();
      try {
        ((FinalizableReference) reference).finalizeReferent();
      } catch (Throwable t) {

  void cleanUp() {
    if (threadStarted) {
      return;
    }

    Reference<?> reference;
    while ((reference = queue.poll()) != null) {
      /*
       * This is for the benefit of phantom references. Weak and soft references will have already
       * been cleared by this point.
       */
      reference.clear();
      try {
        ((FinalizableReference) reference).finalizeReferent();
      } catch (Throwable t) {

        return Equivalence.equals();
      }
    },

    SOFT {
      @Override
      Equivalence<Object> defaultEquivalence() {
        return Equivalence.identity();
      }
    },

    WEAK {
      @Override
      Equivalence<Object> defaultEquivalence() {
        return Equivalence.identity();
      }
    };

    abstract Equivalence<Object> defaultEquivalence();
  }

  /**

import com.google.common.annotations.J2ktIncompatible;
import com.google.common.primitives.Longs;
import com.google.errorprone.annotations.concurrent.GuardedBy;
import com.google.j2objc.annotations.Weak;
import java.time.Duration;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.ReentrantLock;
import java.util.function.BooleanSupplier;

   *
   * <p>Note: the table assumes complete ownership over of {@code backingMap} and the maps returned
   * by {@code factory}. Those objects should not be manually updated and they should not use soft,
   * weak, or phantom references.
   *
   * @param backingMap place to store the mapping from each row key to its corresponding column key
   *     / value map

    return unmodifiableCollectionSubclass(createCollection());
  }

  /**
   * Creates the collection of values for a single key.
   *
   * <p>Collections with weak, soft, or phantom references are not supported. Each call to {@code
   * createCollection} should create a new instance.
   *
   * <p>The returned collection class determines whether duplicate key-value pairs are allowed.
   *

      `I kept all my limbs very supple
    By the use of this ointment--one shilling the box--
      Allow me to sell you a couple?'

    `You are old,' said the youth, `and your jaws are too weak
      For anything tougher than suet;
    Yet you finished the goose, with the bones and the beak--
      Pray how did you manage to do it?'

    `In my youth,' said his father, `I took to the law,