In order to be able to consume the WSDL using an HTTPS URL into webMethods, the Certificate Authority (CA) certificate must exist in the JVM trust store. The truststore is a file named cacerts and it is located at:
The cacerts file (truststore) contains most of the popular certificates from Verisign, Thawte, and others.
Just go ahead and try to import the WSDL via the HTTPS protocol. If the CA certificate is already in the truststore, it will not complain. If it is missing, SSLHandshakeException will occur when attempting to import the WSDL.
If you import the WSDL from a file on disk, then you should be able to successfully import it. You will need the Certificate Authority (CA) certificates into the webMethods IS trust store to successfully call the service.