Adds Java Controller and Metadata support

I've only added metadata support inputs for event sourcing and crdts, I
haven't added it for outputs yet.

Controller support is in full.

build.sbt

@@ -613,7 +613,7 @@ lazy val `java-support` = (project in file("java-support"))
         "com.fasterxml.jackson.core" % "jackson-databind" % "2.9.9.3"
       ),
     javacOptions in Compile ++= Seq("-encoding", "UTF-8"),
-    javacOptions in (Compile, compile) ++= Seq("-source", "1.8", "-target", "1.8"),
+    javacOptions in (Compile, compile) ++= Seq("-source", "11", "-target", "11"),
     akkaGrpcGeneratedSources in Compile := Seq(AkkaGrpc.Server),
     akkaGrpcGeneratedLanguages in Compile := Seq(AkkaGrpc.Scala), // FIXME should be Java, but here be dragons
 
@@ -635,7 +635,8 @@ lazy val `java-support` = (project in file("java-support"))
       sbtprotoc.ProtocPlugin.protobufConfigSettings ++ Seq(
         PB.protoSources ++= {
           val baseDir = (baseDirectory in ThisBuild).value / "protocols"
-          Seq(baseDir / "example")
+          val testSources = sourceDirectory.value / "proto"
+          Seq(baseDir / "example", testSources)
         },
         PB.targets := Seq(
             PB.gens.java -> crossTarget.value / "akka-grpc" / "test"

docs/src/main/paradox/user/lang/java/gettingstarted.md

@@ -180,4 +180,5 @@ Exactly which context parameters are available depend on the type of entity and
 |--------------------------------------------------------|-----------------------|-----------------------|
 | @javadoc[`Context`](io.cloudstate.javasupport.Context) |                       | The super type of all Cloudstate contexts. Every invoker makes a subtype of this available for injection, and method or constructor may accept that sub type, or any super type of that subtype that is a subtype of `Context`. |
 | `java.lang.String` | @javadoc[`@EntityId`](io.cloudstate.javasupport.EntityId) | The ID of the entity. |
-
+| @javadoc[`Metadata`](io.cloudstate.javasupport.Metadata) |                     | The metadata associated with the command. |
+| @javadoc[`CloudEvent`](io.cloudstate.javasupport.CloudEvent) |                 | The CloudEvent metadata associated with the command. May be wrapped in `java.util.Optional`. |

java-support/src/main/java/io/cloudstate/javasupport/CloudEvent.java

@@ -0,0 +1,171 @@
+package io.cloudstate.javasupport;
+
+import java.net.URI;
+import java.time.ZonedDateTime;
+import java.util.Optional;
+
+/** CloudEvent representation of Metadata. */
+public interface CloudEvent {
+
+  /**
+   * The CloudEvent spec version.
+   *
+   * @return The spec version.
+   */
+  String specversion();
+
+  /**
+   * The id of this CloudEvent.
+   *
+   * @return The id.
+   */
+  String id();
+
+  /**
+   * Return a new CloudEvent with the given id.
+   *
+   * @param id The id to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withId(String id);
+
+  /**
+   * The source of this CloudEvent.
+   *
+   * @return The source.
+   */
+  URI source();
+
+  /**
+   * Return a new CloudEvent with the given source.
+   *
+   * @param source The source to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withSource(URI source);
+
+  /**
+   * The type of this CloudEvent.
+   *
+   * @return The type.
+   */
+  String type();
+
+  /**
+   * Return a new CloudEvent with the given type.
+   *
+   * @param type The type to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withType(String type);
+
+  /**
+   * The data content type of this CloudEvent.
+   *
+   * @return The data content type, if set.
+   */
+  Optional<String> datacontenttype();
+
+  /**
+   * Return a new CloudEvent with the given data content type.
+   *
+   * @param datacontenttype The data content type to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withDatacontenttype(String datacontenttype);
+
+  /**
+   * Clear the data content type of this CloudEvent, if set.
+   *
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent clearDatacontenttype();
+
+  /**
+   * The data schema of this CloudEvent.
+   *
+   * @return The data schema, if set.
+   */
+  Optional<URI> dataschema();
+
+  /**
+   * Return a new CloudEvent with the given data schema.
+   *
+   * @param dataschema The data schema to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withDataschema(URI dataschema);
+
+  /**
+   * Clear the data schema of this CloudEvent, if set.
+   *
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent clearDataschema();
+
+  /**
+   * The subject of this CloudEvent.
+   *
+   * @return The subject, if set.
+   */
+  Optional<String> subject();
+
+  /**
+   * Return a new CloudEvent with the given subject.
+   *
+   * @param subject The subject to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withSubject(String subject);
+
+  /**
+   * Clear the subject of this CloudEvent, if set.
+   *
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent clearSubject();
+
+  /**
+   * The time of this CloudEvent.
+   *
+   * @return The time, if set.
+   */
+  Optional<ZonedDateTime> time();
+
+  /**
+   * Return a new CloudEvent with the given time.
+   *
+   * @param time The time to set.
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent withTime(ZonedDateTime time);
+
+  /**
+   * Clear the time of this CloudEvent, if set.
+   *
+   * @return A copy of this CloudEvent.
+   */
+  CloudEvent clearTime();
+
+  /**
+   * Return this CloudEvent represented as Metadata.
+   *
+   * <p>If this CloudEvent was created by {{@link Metadata#asCloudEvent()}}, then any non CloudEvent
+   * metadata that was present will still be present.
+   *
+   * @return This CloudEvent expressed as Cloudstate metadata.
+   */
+  Metadata asMetadata();
+
+  /**
+   * Create a CloudEvent.
+   *
+   * @param id The id of the CloudEvent.
+   * @param source The source of the CloudEvent.
+   * @param type The type of the CloudEvent.
+   * @return The newly created CloudEvent.
+   */
+  static CloudEvent of(String id, URI source, String type) {
+    return Metadata.EMPTY.asCloudEvent(id, source, type);
+  }
+}

java-support/src/main/java/io/cloudstate/javasupport/CloudState.java

@@ -1,12 +1,18 @@
 package io.cloudstate.javasupport;
 
+import akka.actor.ActorSystem;
+import akka.stream.Materializer;
 import com.typesafe.config.Config;
 import com.google.protobuf.Descriptors;
+import io.cloudstate.javasupport.controller.Controller;
+import io.cloudstate.javasupport.controller.ControllerHandler;
 import io.cloudstate.javasupport.crdt.CrdtEntity;
 import io.cloudstate.javasupport.crdt.CrdtEntityFactory;
 import io.cloudstate.javasupport.eventsourced.EventSourcedEntity;
 import io.cloudstate.javasupport.eventsourced.EventSourcedEntityFactory;
 import io.cloudstate.javasupport.impl.AnySupport;
+import io.cloudstate.javasupport.impl.controller.AnnotationBasedControllerSupport;
+import io.cloudstate.javasupport.impl.controller.ControllerService;
 import io.cloudstate.javasupport.impl.crdt.AnnotationBasedCrdtSupport;
 import io.cloudstate.javasupport.impl.crdt.CrdtStatefulService;
 import io.cloudstate.javasupport.impl.eventsourced.AnnotationBasedEventSourcedSupport;
@@ -16,13 +22,14 @@
 import java.util.concurrent.CompletionStage;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.function.Function;
 
 /**
  * The CloudState class is the main interface to configuring entities to deploy, and subsequently
  * starting a local server which will expose these entities to the CloudState Proxy Sidecar.
  */
 public final class CloudState {
-  private final Map<String, StatefulService> services = new HashMap<>();
+  private final Map<String, Function<ActorSystem, Service>> services = new HashMap<>();
   private ClassLoader classLoader = getClass().getClassLoader();
   private String typeUrlPrefix = AnySupport.DefaultTypeUrlPrefix();
   private AnySupport.Prefer prefer = AnySupport.PREFER_JAVA();
@@ -108,14 +115,15 @@ public CloudState registerEventSourcedEntity(
 
     final AnySupport anySupport = newAnySupport(additionalDescriptors);
 
-    services.put(
-        descriptor.getFullName(),
+    EventSourcedStatefulService service =
         new EventSourcedStatefulService(
             new AnnotationBasedEventSourcedSupport(entityClass, anySupport, descriptor),
             descriptor,
             anySupport,
             persistenceId,
-            snapshotEvery));
+            snapshotEvery);
+
+    services.put(descriptor.getFullName(), system -> service);
 
     return this;
   }
@@ -144,12 +152,13 @@ public CloudState registerEventSourcedEntity(
       Descriptors.FileDescriptor... additionalDescriptors) {
     services.put(
         descriptor.getFullName(),
-        new EventSourcedStatefulService(
-            factory,
-            descriptor,
-            newAnySupport(additionalDescriptors),
-            persistenceId,
-            snapshotEvery));
+        service ->
+            new EventSourcedStatefulService(
+                factory,
+                descriptor,
+                newAnySupport(additionalDescriptors),
+                persistenceId,
+                snapshotEvery));
 
     return this;
   }
@@ -178,18 +187,19 @@ public CloudState registerCrdtEntity(
 
     final AnySupport anySupport = newAnySupport(additionalDescriptors);
 
-    services.put(
-        descriptor.getFullName(),
+    CrdtStatefulService service =
         new CrdtStatefulService(
             new AnnotationBasedCrdtSupport(entityClass, anySupport, descriptor),
             descriptor,
-            anySupport));
+            anySupport);
+
+    services.put(descriptor.getFullName(), system -> service);
 
     return this;
   }
 
   /**
-   * Register an CRDt entity factory.
+   * Register a CRDT entity factory.
    *
    * <p>This is a low level API intended for custom (eg, non reflection based) mechanisms for
    * implementing the entity.
@@ -206,7 +216,77 @@ public CloudState registerCrdtEntity(
       Descriptors.FileDescriptor... additionalDescriptors) {
     services.put(
         descriptor.getFullName(),
-        new CrdtStatefulService(factory, descriptor, newAnySupport(additionalDescriptors)));
+        system ->
+            new CrdtStatefulService(factory, descriptor, newAnySupport(additionalDescriptors)));
+
+    return this;
+  }
+
+  /**
+   * Register an annotated Controller service.
+   *
+   * <p>The controller class must be annotated with {@link
+   * io.cloudstate.javasupport.controller.Controller}.
+   *
+   * @param controller The controller object.
+   * @param descriptor The descriptor for the service that this controller implements.
+   * @param additionalDescriptors Any additional descriptors that should be used to look up protobuf
+   *     types when needed.
+   * @return This Cloudstate builder.
+   */
+  public CloudState registerController(
+      Object controller,
+      Descriptors.ServiceDescriptor descriptor,
+      Descriptors.FileDescriptor... additionalDescriptors) {
+
+    Controller controllerAnnotation = controller.getClass().getAnnotation(Controller.class);
+    if (controllerAnnotation == null) {
+      throw new IllegalArgumentException(
+          controller.getClass() + " does not declare an " + Controller.class + " annotation!");
+    }
+
+    final AnySupport anySupport = newAnySupport(additionalDescriptors);
+
+    services.put(
+        descriptor.getFullName(),
+        system ->
+            new ControllerService(
+                new AnnotationBasedControllerSupport(
+                    controller, anySupport, descriptor, Materializer.createMaterializer(system)),
+                descriptor,
+                anySupport));
+
+    return this;
+  }
+
+  /**
+   * Register a Controller handler.
+   *
+   * <p>This is a low level API intended for custom (eg, non reflection based) mechanisms for
+   * implementing the controller.
+   *
+   * @param controller The controller handler.
+   * @param descriptor The descriptor for the service that this controller implements.
+   * @param additionalDescriptors Any additional descriptors that should be used to look up protobuf
+   *     types when needed.
+   * @return This Cloudstate builder.
+   */
+  public CloudState registerController(
+      ControllerHandler controller,
+      Descriptors.ServiceDescriptor descriptor,
+      Descriptors.FileDescriptor... additionalDescriptors) {
+
+    Controller controllerAnnotation = controller.getClass().getAnnotation(Controller.class);
+    if (controllerAnnotation == null) {
+      throw new IllegalArgumentException(
+          controller.getClass() + " does not declare an " + Controller.class + " annotation!");
+    }
+
+    final AnySupport anySupport = newAnySupport(additionalDescriptors);
+
+    ControllerService service = new ControllerService(controller, descriptor, anySupport);
+
+    services.put(descriptor.getFullName(), system -> service);
 
     return this;
   }