Adds cross-linking to Akka and Java SE javadocs (#8331)
Adds cross-linking to Akka and Java SE javadocs (#8331)

* Adds cross-linking to Akka and Java SE javadocs

* Fixes User-Agent name

marcospereira/playframework,marcospereira/playframework,marcospereira/playframework,mkurz/playframework,benmccann/playframework,playframework/playframework,wegtam/playframework,playframework/playframework,wegtam/playframework,benmccann/playframework,Shenker93/playframework,Shenker93/playframework,benmccann/playframework,mkurz/playframework,Shenker93/playframework,marcospereira/playframework,wegtam/playframework,Shenker93/playframework,benmccann/playframework,playframework/playframework,wegtam/playframework,mkurz/playframework,mkurz/playframework