Make ModifyToCreatePolicyTransformer and ModifyToCreateTingTransformer

a SignalTransformer

* Keep them in the persistence service instead of the edge services in order
  to save a roundtrip. The existence checker would not need network
  communication to check if the thing/policy exists because it lives
  on the same service instance

Signed-off-by: Yannic Klem <yannic.klem@bosch.io>

policies/service/src/main/java/org/eclipse/ditto/policies/service/enforcement/pre/ModifyToCreatePolicyTransformer.java

@@ -16,7 +16,7 @@
 import java.util.concurrent.CompletionStage;
 
 import org.eclipse.ditto.base.model.signals.Signal;
-import org.eclipse.ditto.policies.enforcement.pre.PreEnforcer;
+import org.eclipse.ditto.base.service.signaltransformer.SignalTransformer;
 import org.eclipse.ditto.policies.model.signals.commands.modify.CreatePolicy;
 import org.eclipse.ditto.policies.model.signals.commands.modify.ModifyPolicy;
 
@@ -27,7 +27,7 @@
 /**
  * Transforms a ModifyPolicy into a CreatePolicy if the thing does not exist already.
  */
-public final class ModifyToCreatePolicyTransformer implements PreEnforcer {
+public final class ModifyToCreatePolicyTransformer implements SignalTransformer {
 
     private final PolicyExistenceChecker existenceChecker;
 

policies/service/src/main/resources/policies.conf

@@ -6,13 +6,15 @@ ditto {
       extension-class = org.eclipse.ditto.policies.enforcement.pre.PreEnforcerProvider
       extension-config = {
         pre-enforcers = [
-          "org.eclipse.ditto.policies.service.enforcement.pre.ModifyToCreatePolicyTransformer" // always keep this as first pre-enforcer in order to guarantee that all following pre-enforcers know. That the command is creating a policy instead of modifying it
           "org.eclipse.ditto.policies.enforcement.pre.BlockedNamespacePreEnforcer",
           "org.eclipse.ditto.policies.enforcement.pre.CommandWithOptionalEntityPreEnforcer",
           "org.eclipse.ditto.policies.enforcement.pre.CreationRestrictionPreEnforcer"
         ]
       }
     },
+    signal-transformers-provider.extension-config.signal-transformers = [
+      "org.eclipse.ditto.policies.service.enforcement.pre.ModifyToCreatePolicyTransformer" // always keep this as first transformer in order to guarantee that all following transformers know that the command is creating a policy instead of modifying it
+    ]
     snapshot-adapter = {
       extension-class = "org.eclipse.ditto.policies.service.persistence.serializer.PolicyMongoSnapshotAdapter"
     }

things/service/src/main/java/org/eclipse/ditto/things/service/enforcement/pre/ModifyToCreateThingTransformer.java

@@ -16,8 +16,8 @@
 import java.util.concurrent.CompletionStage;
 
 import org.eclipse.ditto.base.model.signals.Signal;
+import org.eclipse.ditto.base.service.signaltransformer.SignalTransformer;
 import org.eclipse.ditto.json.JsonObject;
-import org.eclipse.ditto.policies.enforcement.pre.PreEnforcer;
 import org.eclipse.ditto.things.model.signals.commands.modify.CreateThing;
 import org.eclipse.ditto.things.model.signals.commands.modify.ModifyThing;
 
@@ -28,7 +28,7 @@
 /**
  * Transforms a ModifyThing into a CreateThing if the thing does not exist already.
  */
-public final class ModifyToCreateThingTransformer implements PreEnforcer {
+public final class ModifyToCreateThingTransformer implements SignalTransformer {
 
     private final ThingExistenceChecker existenceChecker;
 

things/service/src/main/resources/things.conf

@@ -7,13 +7,15 @@ ditto {
       extension-class = org.eclipse.ditto.policies.enforcement.pre.PreEnforcerProvider
       extension-config = {
         pre-enforcers = [
-          "org.eclipse.ditto.things.service.enforcement.pre.ModifyToCreateThingTransformer", // always keep this as first pre-enforcer in order to guarantee that all following pre-enforcers know. That the command is creating a thing instead of modifying it
           "org.eclipse.ditto.policies.enforcement.pre.BlockedNamespacePreEnforcer",
           "org.eclipse.ditto.policies.enforcement.pre.CommandWithOptionalEntityPreEnforcer",
           "org.eclipse.ditto.policies.enforcement.pre.CreationRestrictionPreEnforcer"
         ]
       }
     }
+    signal-transformers-provider.extension-config.signal-transformers = [
+      "org.eclipse.ditto.things.service.enforcement.pre.ModifyToCreateThingTransformer" // always keep this as first transformer in order to guarantee that all following transformers know that the command is creating a policy instead of modifying it
+    ]
     snapshot-adapter = {
       extension-class = "org.eclipse.ditto.things.service.persistence.serializer.ThingMongoSnapshotAdapter"
     }