default boolean isAvailable(final SamlRegisteredService service) {
        return supports(service);
    }
Is the resolver available and able to resolve metadata?
This method may contact the metadata source checking for
the source availability.

@param service the service
@return true /false
support/cas-server-support-saml-idp-metadata/src/main/java/org/apereo/cas/support/saml/services/idp/metadata/cache/resolver/SamlRegisteredServiceMetadataResolver.java