@Override
    public @Nullable V computeIfPresent(
        K key, BiFunction<? super K, ? super @NonNull V, ? extends @Nullable V> remappingFunction) {
      synchronized (mutex) {
        return delegate().computeIfPresent(key, remappingFunction);
      }
    }

    @Override
    public @Nullable V compute(
        K key,
        BiFunction<? super K, ? super @Nullable V, ? extends @Nullable V> remappingFunction) {

    }

    @Override
    public @Nullable V computeIfPresent(
        K key, BiFunction<? super K, ? super @NonNull V, ? extends @Nullable V> remappingFunction) {
      throw new UnsupportedOperationException();
    }

    @Override
    public @Nullable V compute(
        K key,
        BiFunction<? super K, ? super @Nullable V, ? extends @Nullable V> remappingFunction) {

import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.DoubleConsumer;
import java.util.function.IntConsumer;
import java.util.function.LongConsumer;
import java.util.stream.BaseStream;

import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import org.jspecify.annotations.Nullable;

/**
 * CompactHashMap is an implementation of a Map. All optional operations (put and remove) are

import java.util.PrimitiveIterator;
import java.util.Spliterator;
import java.util.Spliterators;
import java.util.Spliterators.AbstractSpliterator;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Consumer;
import java.util.function.DoubleConsumer;
import java.util.function.IntConsumer;
import java.util.function.LongConsumer;
import java.util.stream.BaseStream;

  @Override
  public @Nullable V computeIfPresent(
      K key, BiFunction<? super K, ? super V, ? extends @Nullable V> function) {
    checkNotNull(key);
    checkNotNull(function);
    return compute(key, (k, oldValue) -> (oldValue == null) ? null : function.apply(k, oldValue));
  }

  @Override
  public @Nullable V merge(
      K key, V newValue, BiFunction<? super V, ? super V, ? extends @Nullable V> function) {

import java.util.Collections;
import java.util.Date;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.function.BiConsumer;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.UnaryOperator;
import java.util.regex.Pattern;
import java.util.stream.Collectors;

import org.apache.logging.log4j.LogManager;