@POST
    @Restricted(NoExternalUse.class)
    public FormValidation doCheckNewSource(@QueryParameter String newSource) {
        Jenkins.get().checkPermission(Jenkins.ADMINISTER);
        String normalizedSource = Util.fixEmptyAndTrim(newSource);
        if (normalizedSource == null) {
            return FormValidation.ok(); // empty, do nothing
        }
        List<String> candidateSources = new ArrayList<>();
        for (String candidateSource : inputToCandidateSources(normalizedSource)) {
            File file = new File(candidateSource);
            if (!file.exists() && !ConfigurationAsCode.isSupportedURI(candidateSource)) {
                return FormValidation.error(
                        "Configuration cannot be applied. File or URL cannot be parsed or do not exist.");
            }
            candidateSources.add(candidateSource);
        }
        try {
            List<YamlSource> candidates = getConfigFromSources(candidateSources);
            final Map<Source, String> issues = checkWith(candidates);
            final JSONArray errors = collectProblems(issues, "error");
            if (!errors.isEmpty()) {
                return FormValidation.error(errors.toString());
            }
            final JSONArray warnings = collectProblems(issues, "warning");
            if (!warnings.isEmpty()) {
                return FormValidation.warning(warnings.toString());
            }
            return FormValidation.okWithMarkup("The configuration can be applied");
        } catch (ConfiguratorException | IllegalArgumentException e) {
            return FormValidation.error(
                    e, e.getCause() == null ? e.getMessage() : e.getCause().getMessage());
        }
    }
Name of the category for this management link.
TODO: Use getCategory when core requirement is greater or equal to 2.226
plugin/src/main/java/io/jenkins/plugins/casc/ConfigurationAsCode.java