code: private boolean chunkInStorage(String spaceId, String contentId, String checksum) {
          try {
              if (contentStore.contentExists(spaceId, contentId)) { // dc file exists
                  Map<String, String> props =
                      contentStore.getContentProperties(spaceId, contentId);
                  String dcChecksum = props.get(ContentStore.CONTENT_CHECKSUM);
                  if (null != checksum && null != dcChecksum && checksum.equals(dcChecksum)) {
                      return true; // File with matching checksum already in DuraCloud
                  } else {
                      return false; // File exists in DuraCloud, but checksums don't match
                  }
              } else {
                  return false; // File does not exist in DuraCloud
              }
          } catch (ContentStoreException e) {
              return false; // File does not exist in DuraCloud
          }
      }
docs: /*
  Determines if a file chunk exists in DuraCloud storage with the given checksum