Add missing TargetAggregateIdentifier in test command

Author: sandjelkovic

kotlin/src/test/kotlin/org/axonframework/extensions/kotlin/testObjects.kt

@@ -1,5 +1,7 @@
 package org.axonframework.extensions.kotlin
 
+import org.axonframework.modelling.command.TargetAggregateIdentifier
+
 /**
  * Simple Query class to be used in tests.
  */
@@ -8,4 +10,4 @@ internal data class ExampleQuery(val value: Number)
 /**
  * Simple Command class to be used in tests.
  */
-internal data class ExampleCommand(val id: String)
+internal data class ExampleCommand(@TargetAggregateIdentifier val id: String)