SseEventSource cannot see the JAXRS_DEFAULT_SSE_BUILDER in OSGI

Because the package **org.glassfish.jersey.media.sse.internal** is not exported in the jersey-media-sse bundle,e.g. the JaxRs client is not able to load the default SSE builder.

This is a constellation that will never work.
A possible solution could be to introduce a factory in the SSE that can be instanciated reflectivley and then create the builder instance in the **javax.ws.rs.ext.sse.FactoryFinder#find** call

Start at javax.ws.rs.ext.sse.FactoryFinder#find and inspect how the default SSE builder is loaded for the SseEventSource. Then examine the jersey-media-sse bundle and its org.glassfish.jersey.media.sse.internal package export. Done means the JAX-RS client can load JAXRS_DEFAULT_SSE_BUILDER in OSGi, with the proposed reflective factory considered against the existing loading path.

Written by the indexing model from the issue text.