We still want ServiceLoader based discovery to work in non-modular environments, rather than adding a new element I think we rename the following: -

                    <xsd:element name="use-module-providers" type="module-ref-type"/>
                    <xsd:element name="use-module-sasl-factory" type="module-ref-type" />

To use-service-loader-*

Then make the attributes of module-ref-type optional and use the ClassLoader of the parser.

I think in 99% of cases we will be looking for Elytron implementations so as the ClassLoader was able to load the parser it should have the rest of the Elytron service loader services..