Java Implementations?

Hello,

I am looking for Java implementations of JSON-LD to integrate into an RDF database.  I have done some looking around and found the following efforts [1,2,3,4], however I have no sense of how active these different projects might be, how well they are tracking the emerging specification, and how well they might interoperate with the JSON-LD ecosystem (i.e., can they be used to interchange data with other JSON-LD processors or do they just talk with themselves).

Thanks in advance,
Bryan

[1]<https://sourceforge.net/apps/trac/bigdata/changeset/1> http://code.google.com/p/jsonld4j/
[2]<https://sourceforge.net/apps/trac/bigdata/changeset/2> https://github.com/tristan/jsonld-java
[3]<https://sourceforge.net/apps/trac/bigdata/changeset/3> http://code.google.com/p/iks-project/source/browse/sandbox/fise/trunk/jersey/src/main/java/eu/iksproject/fise/jsonld/JsonLd.java?spec=svn1048&r=1048
[4]<https://sourceforge.net/apps/trac/bigdata/changeset/4> http://svn.apache.org/repos/asf/incubator/stanbol/trunk/commons/jsonld/src/main/java/org/apache/stanbol/commons/jsonld/JsonLd.java