JSON-LD reader not reading namespace prefixes

[Holger Knublauch]

(I hope this is the right place to ask this question).
Looking at

https://github.com/jsonld-java/jsonld-java/blob/master/integration/jena/src/main/java/com/github/jsonldjava/jena/JsonLDReader.java

it seems that the current JSON-LD reader does not copy the prefix 
definitions into the target Jena model, even though the writer is 
correctly creating them.

Thanks
Holger