code: private Collection<String> processAllowedEndpoints(Collection<String> endpointIds) {
          if (endpointIds == null || endpointIds.isEmpty())
              return null;
  
          return endpointIds;
      }
docs: Check the incoming list of endpoint pids (from configuration). If the list is null
  or empty, return null. Otherwise return the list.
  
  @param endpointIds
  @return null (all endpoints), or trimmed list of allowed endpoints
  @see #acceptFromEndpoint(String)