Create 'commandAuthorization' when deserializing aggregate

Aggregates are deserialized when using Axon snapshots.

Fixes #73

domain/command-handling/src/main/java/io/motown/domain/chargingstation/ChargingStation.java

@@ -25,6 +25,9 @@
 import org.axonframework.eventsourcing.annotation.AggregateIdentifier;
 import org.axonframework.eventsourcing.annotation.EventSourcingHandler;
 
+import java.io.IOException;
+import java.io.ObjectInputStream;
+
 public class ChargingStation extends AbstractAnnotatedAggregateRoot {
 
     private static final long serialVersionUID = -3089562761704323707L;
@@ -634,4 +637,18 @@ private void checkCommandAllowed(IdentityContext identityContext, Class commandC
         }
     }
 
+    /**
+     * Ensures the transient fields are populated upon deserialization. This occurs when an aggregate is read from
+     * snapshot.
+     *
+     * @param in input stream with de serialized object
+     * @throws IOException if an I/O error occurs.
+     * @throws ClassNotFoundException if the class of a serialized object could not be found.
+     */
+    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
+        in.defaultReadObject();
+
+        commandAuthorization = new SimpleCommandAuthorization();
+    }
+
 }