code: protected ValidationResult getCachedResult(String certFingerprint) {
  
      CachedValidationResult cvr = validationResultsCache.get(certFingerprint);
  
      if (cvr == null)
        return null;
  
      if (!cachedValidationResultHasExpired(cvr, System.currentTimeMillis())) {
        return cvr.getResult();
      }
  
      validationResultsCache.remove(certFingerprint, cvr);
      return null;
    }
docs: Gets a validation result from the memory cache
  
  @param certFingerprint
  the certificate fingerprint for the certificate at the top of the
  chain
  @return the validation result, if found. <code>null</code> otherwise.