code: @Synchronized
      protected Map<String, List<Object>> retrievePersonAttributes(final String principalId, final Credential credential) {
          return CoreAuthenticationUtils.retrieveAttributesFromAttributeRepository(this.attributeRepository, principalId, activeAttributeRepositoryIdentifiers);
      }
docs: Retrieve person attributes map.
  
  @param principalId the principal id
  @param credential  the credential whose id we have extracted. This is passed so that implementations
  can extract useful bits of authN info such as attributes into the principal.
  @return the map