stream.defaultReadObject();
    int keyCount = stream.readInt();
    if (keyCount < 0) {
      throw new InvalidObjectException("Invalid key count " + keyCount);
    }
    ImmutableMap.Builder<Object, ImmutableList<Object>> builder = ImmutableMap.builder();
    int tmpSize = 0;

    for (int i = 0; i < keyCount; i++) {
      Object key = requireNonNull(stream.readObject());

    int keyCount = stream.readInt();
    if (keyCount < 0) {
      throw new InvalidObjectException("Invalid key count " + keyCount);
    }
    ImmutableMap.Builder<Object, ImmutableSet<Object>> builder = ImmutableMap.builder();
    int tmpSize = 0;

    for (int i = 0; i < keyCount; i++) {
      Object key = requireNonNull(stream.readObject());

    int keyCount = stream.readInt();
    if (keyCount < 0) {
      throw new InvalidObjectException("Invalid key count " + keyCount);
    }
    ImmutableMap.Builder<Object, ImmutableSet<Object>> builder = ImmutableMap.builder();
    int tmpSize = 0;

    for (int i = 0; i < keyCount; i++) {
      Object key = requireNonNull(stream.readObject());

	// subsequent request to get the next set of object keys.
	ContinuationToken     string `xml:"ContinuationToken,omitempty"`
	NextContinuationToken string `xml:"NextContinuationToken,omitempty"`

	KeyCount  int
	MaxKeys   int
	Delimiter string `xml:"Delimiter,omitempty"`
	// A flag that indicates whether or not ListObjects returned all of the results
	// that satisfied the search criteria.
	IsTruncated bool