docs: public static Map<String, SavedAttachment> findExistingAttachments(
              Map<String, ? extends Attachment> attachments) {
          Map<String, SavedAttachment> existingAttachments = new HashMap<String, SavedAttachment>();
          for (Map.Entry<String, ? extends Attachment> a : attachments.entrySet()) {
              if (a instanceof SavedAttachment) {
                  existingAttachments.put(a.getKey(), (SavedAttachment)a.getValue());
              }
          }
          return existingAttachments;
      }