OZG-7689 readd workaroung for jackson configuration

src/main/java/de/ozgcloud/processor/vorgang/Vorgang.java

@@ -24,6 +24,7 @@
 package de.ozgcloud.processor.vorgang;
 
 import java.time.ZonedDateTime;
+import java.util.Objects;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
 import com.fasterxml.jackson.annotation.JsonProperty.Access;
@@ -62,6 +63,12 @@ public class Vorgang {
 		private String event;
 		private String status;
 		private ZonedDateTime createdAt;
+
+		// TODO workaround for faulty jackson configuration
+		@JsonProperty
+		public String getCreatedAt() {
+			return Objects.isNull(createdAt) ? null : createdAt.toString();
+		}
 	}
 
 	public Vorgang withEvent(String event) {