Web services should be the only server-side layer to get data and do operations from server-side extensions. Maintaining Java components is too costly and does not worth it.
If a plugin extension, for example a new WS, requires some data (measures, issues, ...), then it has to call existing web services. Of course the call must not use the HTTP stack. It should directly call the underlying Java implementations. A solution is to have a in-process mode of ws-client (see