Play server refuses to start with google-cloud dependency

Question

I am trying to use google cloud data store in my play scala service (Play v2.5.7), because of which I am adding the google-cloud dependency in my build.sbt

"com.google.cloud" % "google-cloud" % "0.4.0",

The server starts up fine without the dependency. However after adding the dependency, the play server start gives an error:

[info] Loading global plugins from /<redacted>/.sbt/0.13/plugins
[info] Loading project definition from /<redacted>/dev/auth-svc/project
[info] Set current project to authsvc (in build file:/<redacted>/auth-svc/)

--- (Running the application, auto-reloading is enabled) ---

java.lang.NullPointerException
        at io.netty.channel.group.DefaultChannelGroup.add(DefaultChannelGroup.java:146)
        at play.core.server.NettyServer.bind(NettyServer.scala:140)
        at play.core.server.NettyServer.play$core$server$NettyServer$$bindChannel(NettyServer.scala:224)
        at play.core.server.NettyServer$$anonfun$1.apply(NettyServer.scala:216)
        at play.core.server.NettyServer$$anonfun$1.apply(NettyServer.scala:216)
        at scala.Option.map(Option.scala:146)
        at play.core.server.NettyServer.<init>(NettyServer.scala:216)
        at play.core.server.NettyServerProvider.createServer(NettyServer.scala:279)
        at play.core.server.NettyServerProvider.createServer(NettyServer.scala:278)
        at play.core.server.DevServerStart$$anonfun$mainDev$1.apply(DevServerStart.scala:235)
        at play.core.server.DevServerStart$$anonfun$mainDev$1.apply(DevServerStart.scala:65)
        at play.utils.Threads$.withContextClassLoader(Threads.scala:21)
        at play.core.server.DevServerStart$.mainDev(DevServerStart.scala:64)
        at play.core.server.DevServerStart$.mainDevHttpMode(DevServerStart.scala:54)
        at play.core.server.DevServerStart.mainDevHttpMode(DevServerStart.scala)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at play.runsupport.Reloader$.startDevMode(Reloader.scala:234)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.devModeServer$lzycompute$1(PlayRun.scala:74)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.play$sbt$run$PlayRun$$anonfun$$anonfun$$anonfun$$devModeServer$1(PlayRun.scala:74)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.apply(PlayRun.scala:100)
        at play.sbt.run.PlayRun$$anonfun$playRunTask$1$$anonfun$apply$2$$anonfun$apply$3.apply(PlayRun.scala:53)
        at scala.Function1$$anonfun$compose$1.apply(Function1.scala:47)
[trace] Stack trace suppressed: run last compile:run for the full output.
[error] (compile:run) java.lang.reflect.InvocationTargetException
[error] Total time: 1 s, completed Oct 6, 2016 12:50:18 AM

Any clues?

Answer 1

The solution OP says worked can work in two ways: either downgrading google-cloud to 0.2.2 or downgrading Play back to 2.4.6. There is a related extensive discussion to be found in the Play Framework Google Group, an there's a workaround-type solution proposed in the “Upgrade to Netty 4.1.5.Final and Akka Streams 2.4.10” conversation on github.