@Override
  public boolean equals(@Nullable Object o) {
    if (o == this) {
      return true;
    }
    if (o instanceof SimpleCacheKey) {
      final SimpleCacheKey otherKey = (SimpleCacheKey) o;
      return mKey.equals(otherKey.mKey);
    }
    return false;
  }
{@link CacheKey} implementation that is a simple wrapper around a {@link String} object.

<p>Users of CacheKey should construct it by providing a unique string that unambiguously
identifies the cached resource.
imagepipeline-base/src/main/java/com/facebook/cache/common/SimpleCacheKey.java