protected List<Authorizer> computeAuthorizers(final WebContext context, final List<UserProfile> profiles, final String authorizersValue,
                                                  final Map<String, Authorizer> authorizersMap, final List<Client> clients) {
        final List<Authorizer> authorizers;
        if (StringUtils.isBlank(authorizersValue)) {
            authorizers = computeDefaultAuthorizers(context, profiles, clients, authorizersMap);
        } else {
            if (authorizersValue.trim().startsWith(Pac4jConstants.ADD_ELEMENT)) {
                val authorizerNames = StringUtils.substringAfter(authorizersValue, Pac4jConstants.ADD_ELEMENT);
                authorizers = computeDefaultAuthorizers(context, profiles, clients, authorizersMap);
                authorizers.addAll(computeAuthorizersFromNames(authorizerNames, authorizersMap));
            } else {
                authorizers = computeAuthorizersFromNames(authorizersValue, authorizersMap);
            }
        }
        return authorizers;
    }
<p>computeAuthorizers.</p>

@param context a {@link WebContext} object
@param profiles a {@link List} object
@param authorizersValue a {@link String} object
@param authorizersMap a {@link Map} object
@param clients a {@link List} object
@return a {@link List} object
pac4j-core/src/main/java/org/pac4j/core/authorization/checker/DefaultAuthorizationChecker.java