=act #17239 Add akka.japi.function with variance

Needed by Akka Streams. Old functions placed in akka.japi will be deprecated
in 2.4

(cherry picked from commit 99628f408295070848af6c23b1d722057069e660)

+act #17392 Include generated japi.function from akka-stream

* add boilerplate plugin
* make them Serializable to be able to grab line number for Java 8 lambdas

(cherry picked from commit d5950a13d2f123d2101d56f0a8a86a2097dda8e1)

akka-actor/build.sbt

@@ -14,3 +14,6 @@ OSGi.actor
 libraryDependencies ++= Dependencies.actor
 
 MimaKeys.previousArtifact := akkaPreviousArtifact("akka-actor").value
+
+spray.boilerplate.BoilerplatePlugin.Boilerplate.settings
+

akka-actor/src/main/boilerplate/akka/japi/function/Functions.scala.template

@@ -0,0 +1,29 @@
+/**
+ * Copyright (C) 2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.japi.function
+
+[3..22#/**
+ * A Function interface. Used to create 1-arg first-class-functions is Java.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(##1L)
+trait Function1[[#-T1#], +R] extends java.io.Serializable {
+  @throws(classOf[Exception])
+  def apply([#arg1: T1#]): R
+}#
+
+]
+
+[2..#/**
+ * A Consumer interface. Used to create 1-arg consumers in Java.
+ * A Procedure is like a Function, but it doesn't produce a return value.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(##1L)
+trait Procedure1[[#-T1#]] extends java.io.Serializable {
+  @throws(classOf[Exception])
+  def apply([#arg1: T1#]): Unit
+}#
+
+]

akka-actor/src/main/scala/akka/japi/function/Function.scala

@@ -0,0 +1,66 @@
+/**
+ * Copyright (C) 2009-2015 Typesafe Inc. <http://www.typesafe.com>
+ */
+package akka.japi.function
+
+/**
+ * A Function interface. Used to create first-class-functions is Java.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(1L)
+trait Function[-T, +R] extends java.io.Serializable {
+  @throws(classOf[Exception])
+  def apply(param: T): R
+}
+
+/**
+ * A Function interface. Used to create 2-arg first-class-functions is Java.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(1L)
+trait Function2[-T1, -T2, +R] extends java.io.Serializable {
+  @throws(classOf[Exception])
+  def apply(arg1: T1, arg2: T2): R
+}
+
+/**
+ * A Procedure is like a Function, but it doesn't produce a return value.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(1L)
+trait Procedure[-T] extends java.io.Serializable {
+  @throws(classOf[Exception])
+  def apply(param: T): Unit
+}
+
+/**
+ * An executable piece of code that takes no parameters and doesn't return any value.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(1L)
+trait Effect extends java.io.Serializable {
+  @throws(classOf[Exception])
+  def apply(): Unit
+}
+
+/**
+ * Java API: Defines a criteria and determines whether the parameter meets this criteria.
+ * `Serializable` is needed to be able to grab line number for Java 8 lambdas.
+ */
+@SerialVersionUID(1L)
+trait Predicate[-T] extends java.io.Serializable {
+  def test(param: T): Boolean
+}
+
+/**
+ * A constructor/factory, takes no parameters but creates a new value of type T every call.
+ */
+@SerialVersionUID(1L)
+trait Creator[+T] extends Serializable {
+  /**
+   * This method must return a different instance upon every call.
+   */
+  @throws(classOf[Exception])
+  def create(): T
+}
+

project/plugins.sbt

@@ -1,7 +1,6 @@
 resolvers += Classpaths.typesafeResolver
 
 resolvers += "jgit-repo" at "http://download.eclipse.org/jgit/maven"
-
 // need this to resolve http://jcenter.bintray.com/org/jenkins-ci/jenkins/1.26/
 // which is used by plugin "org.kohsuke" % "github-api" % "1.68"
 resolvers += Resolver.jcenterRepo
@@ -38,3 +37,6 @@ addSbtPlugin("com.typesafe.sbt" % "sbt-native-packager" % "1.0.0-RC1")
 addSbtPlugin("net.virtual-void" % "sbt-dependency-graph" % "0.7.4")
 
 libraryDependencies += "org.kohsuke" % "github-api" % "1.68"
+
+addSbtPlugin("io.spray" % "sbt-boilerplate" % "0.5.9")
+