public static Set<AttachmentId> getAttachemntIds(ProtocolWaveletDelta delta) {
Set<AttachmentId> ids = new HashSet<AttachmentId>();
for (int i=0; i < delta.getOperationCount(); i++) {
ProtocolWaveletOperation op = delta.getOperation(i);
if (op.hasMutateDocument()) {
MutateDocument doc = op.getMutateDocument();
for (int c = 0; c < doc.getDocumentOperation().getComponentCount(); c++) {
Component comp = doc.getDocumentOperation().getComponent(c);
ElementStart start = comp.getElementStart();
if (ImageConstants.TAGNAME.equals(start.getType())) {
for (int a=0; a < start.getAttributeCount(); a++) {
Component.KeyValuePair attr = start.getAttribute(a);
if (ImageConstants.ATTACHMENT_ATTRIBUTE.equals(attr.getKey())) {