code: public static String getCandidateSurt(UsableURI u) {
          if (u == null) {
              return null;
          }
          String candidateSurt = u.getSurtForm();
          // also want to treat https as http
          candidateSurt = coerceFromHttpsForComparison(candidateSurt);
          return candidateSurt;
      }
docs: Calculate the SURT form URI to use as a candidate against prefixes
  from the given Object (CandidateURI or UURI)
  
  @param object CandidateURI or UURI
  @return SURT form of URI for evaluation, or null if unavailable