code: public static String getAttachmentUrl(String applicationId, UUID callId, String attachmentName) {
          return String.format("%s%s/%s/%s", ATTACHMENT_URL_BASE, applicationId, callId.toString(), attachmentName);
      }
docs: Returns the name of the content provider formatted correctly for constructing URLs.
  @param applicationId the Facebook application ID of the application
  @return the String to use as the authority portion of a content URI.