code: public ExternalServiceAlertConditionCache externalServiceAlertConditions(long policyId)
      {
          ExternalServiceAlertConditionCache cache = externalServiceConditions.get(policyId);
          if(cache == null)
              externalServiceConditions.put(policyId, cache = new ExternalServiceAlertConditionCache(policyId));
          return cache;
      }
docs: Returns the cache of external service alert conditions for the given policy, creating one if it doesn't exist .
  @param policyId The id of the policy for the cache of external service alert conditions
  @return The cache of external service alert conditions for the given policy