protected Authorizer retrieveAuthorizer(final String authorizerName, final Map<String, Authorizer> authorizersMap) {
        Authorizer authorizer = null;
        for (val entry : authorizersMap.entrySet()) {
            if (areEqualsIgnoreCaseAndTrim(entry.getKey(), authorizerName)) {
                authorizer = entry.getValue();
                break;
            }
        }
        if (authorizer == null) {
            if (DefaultAuthorizers.CSRF_CHECK.equalsIgnoreCase(authorizerName)) {
                return CSRF_AUTHORIZER;
            } else if (DefaultAuthorizers.IS_ANONYMOUS.equalsIgnoreCase(authorizerName)) {
                return IS_ANONYMOUS_AUTHORIZER;
            } else if (DefaultAuthorizers.IS_AUTHENTICATED.equalsIgnoreCase(authorizerName)) {
                return IS_AUTHENTICATED_AUTHORIZER;
            } else if (DefaultAuthorizers.IS_FULLY_AUTHENTICATED.equalsIgnoreCase(authorizerName)) {
                return IS_FULLY_AUTHENTICATED_AUTHORIZER;
            } else if (DefaultAuthorizers.IS_REMEMBERED.equalsIgnoreCase(authorizerName)) {
                return IS_REMEMBERED_AUTHORIZER;
            }
        }
        return authorizer;
    }
<p>retrieveAuthorizer.</p>

@param authorizerName a {@link String} object
@param authorizersMap a {@link Map} object
@return a {@link Authorizer} object
pac4j-core/src/main/java/org/pac4j/core/authorization/checker/DefaultAuthorizationChecker.java