checkNotNull(value);
    Timestamped<V> oldValue = cachingHashMap.put(key, new Timestamped<V>(value, ticker));
    if (oldValue == null) {
      return null;
    }
    alertListenerIfPresent(key, oldValue.getValue(), RemovalCause.REPLACED);
    return oldValue.getValue();
  }

  @CanIgnoreReturnValue
  @Override
  public V remove(Object key) {
    Timestamped<V> stamped = cachingHashMap.remove(key);

import org.eclipse.aether.metadata.Metadata;
import org.eclipse.aether.util.ConfigUtils;

/**
 * Maven remote GAV level metadata generator.
 * <p>
 * Remote snapshot metadata converts artifact on-the-fly to use timestamped snapshot version, and enlist it accordingly.
 */
class RemoteSnapshotMetadataGenerator implements MetadataGenerator {

    private final Map<Object, RemoteSnapshotMetadata> snapshots;

    private final Date timestamp;