#vulnerable code 
                                private String[] getReferrer() {
        String referrer = uriInfo.getQueryParameters().getFirst("referrer");
        if (referrer == null) {
            return null;
        }

        String referrerUri = uriInfo.getQueryParameters().getFirst("referrer_uri");

        ApplicationModel application = realm.getApplicationByName(referrer);
        if (application != null) {
            if (referrerUri != null) {
                referrerUri = TokenService.verifyRedirectUri(uriInfo, referrerUri, application);
            } else {
                referrerUri = ResolveRelative.resolveRelativeUri(uriInfo.getRequestUri(), application.getBaseUrl());
            }

            if (referrerUri != null) {
                return new String[]{referrer, referrerUri};
            }
        } else if (referrerUri != null) {
            ClientModel client = realm.getOAuthClient(referrer);
            if (client != null) {
                referrerUri = TokenService.verifyRedirectUri(uriInfo, referrerUri, application);

                if (referrerUri != null) {
                    return new String[]{referrer, referrerUri};
                }
            }
        }

        return null;
    } 
                            #location 12 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                private String[] getReferrer() {
        String referrer = uriInfo.getQueryParameters().getFirst("referrer");
        if (referrer == null) {
            return null;
        }

        String referrerUri = uriInfo.getQueryParameters().getFirst("referrer_uri");

        ApplicationModel application = realm.getApplicationByName(referrer);
        if (application != null) {
            if (referrerUri != null) {
                referrerUri = TokenService.verifyRedirectUri(uriInfo, referrerUri, realm, application);
            } else {
                referrerUri = ResolveRelative.resolveRelativeUri(uriInfo.getRequestUri(), application.getBaseUrl());
            }

            if (referrerUri != null) {
                return new String[]{referrer, referrerUri};
            }
        } else if (referrerUri != null) {
            ClientModel client = realm.getOAuthClient(referrer);
            if (client != null) {
                referrerUri = TokenService.verifyRedirectUri(uriInfo, referrerUri, realm, application);

                if (referrerUri != null) {
                    return new String[]{referrer, referrerUri};
                }
            }
        }

        return null;
    }