Add sbt-java-formatter for java code formatting.

.sbt-java-formatter.conf

@@ -0,0 +1,35 @@
+//ignore by files
+//  1. the protobuf generated messages
+ignored-files = [
+  "ArteryControlFormats.java",
+  "ContainerFormats.java",
+  "SystemMessageFormats.java",
+  "WireFormats.java",
+  "StreamRefMessages.java",
+  //in tests
+  "ProtobufProtocol.java"
+]
+
+//ignore by pacakges:
+//  1. adated source code
+//  2. protobuf generated messages
+ignored-packages = [
+  "akka.dispatch",
+  "akka.protobuf",
+  "sun.reflect",
+  "akka.cluster.protobuf.msg",
+  "akka.cluster.metrics.protobuf.msg",
+  "akka.cluster.sharding.protobuf.msg",
+  "akka.cluster.sharding.typed.internal.protobuf",
+  "akka.cluster.client.protobuf.msg",
+  "akka.cluster.pubsub.protobuf.msg",
+  "akka.cluster.typed.internal.protobuf",
+  "akka.cluster.ddata.protobuf.msg",
+  "akka.remote.testconductor",
+  "akka.persistence.serialization",
+  //in tests
+  "akka.remote.artery.protobuf",
+  //in docs
+  "docs.ddata.protobuf.msg",
+  "docs.persistence.proto"
+]