How to validate web page link is broken or not?

hi,
you are missing ssl certification
SSLHandshakeException: java.security.cert.CertificateException
your urls are using ssl certification
ouh and here you have typo
for(String aURL : allURLs) {
println aURL;
WebUI.verifyLinksAccessible(allURLs)
}
should be
WebUI.verifyLinksAccessible(aURL)