SoapUI won't play with Burp: SSLHandshakeException -unable to find valid certification path

I'm trying to use SoapUI along with Burpsuite Pro. I've set up the appropriate proxy settings in SoapUI but when I try to issue a request, I get the error:

Although I was able to find that this question had been previously asked, it was answered but the person who posted it never replied so it was closed without resolution.  Please advise.  Thanks.