Add tests to verify jsonrpc2 null results
Add tests to verify jsonrpc2 null results

mediocregopher/rpc,QianChenglong/rpc,Gorilla/rpc,somyaSjsu/rpc,mediocregopher/rpc,gorilla/rpc,segmentio/gorilla-rpc,mediocregopher/rpc,jacobxk/rpc,Limard/rpcHttp,jackmanlabs/rpc,somyaSjsu/rpc,jackmanlabs/rpc,jacobxk/rpc,QianChenglong/rpc,somyaSjsu/rpc,jackmanlabs/rpc,Gorilla/rpc,Limard/rpcHttp,Limard/rpc,segmentio/gorilla-rpc,jacobxk/rpc,Gorilla/rpc,ingresso-group/rpc,Limard/rpc,Limard/rpcHttp,gorilla/rpc,gorilla/rpc,ingresso-group/rpc,QianChenglong/rpc,Limard/rpc,ingresso-group/rpc,segmentio/gorilla-rpc