Deprecated Json4J Providers still registered. Usage by default cannot be prevented

[jhemm2]

The Providers from the Json4JProvidersRegistryare deprecated but still registered by default. This behavior cannot be prevented when using the default OslcClient. This leads to malformed json when the OslcRdfJsonProvideris used as MessageBodyWriter.

This issue occurs since lyo 6.0.0 but may have been in there earlier.

Provide an option to prevent registration of providers by default and to add them manually when needed.

[berezovskyi]

Thanks, the PR looks good and this is a good issue to fix -- approved, let's wait till Jad had time to check it out.

Many years ago I had a number of similar problems - but from the OSLC Server side, needing to have pure JSON/XML endpoints. As a result, I made some changes/workarounds but did not merge them in the end because there was no user feedback and I did not want to break something that worked for all users. If you are interested / need it, I will be happy if you pick up those changes, change them as you see fit and submit as a PR:

• https://github.com/eclipse-lyo/lyo.core/pull/76 - replaces multiple providers that simply call Jena with different params with a single provider. Extra considerations in https://github.com/eclipse-lyo/lyo.core/pull/9
• https://github.com/eclipse-lyo/lyo/pull/277 - allows to more precisely control the serialization for a given RDF format. Two ideas: there were some problems with RDF-XML/ABBREV with Jazz and newer Jena versions - good to have more control. And the other one was to use pretty-printable serializations in development and streaming serializations in prod.