Ensure that key is always only the id without the namespace.

src/main/kotlin/KafkaTopology.kt

@@ -24,6 +24,7 @@ import ch.memobase.settings.SettingsLoader
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.module.kotlin.registerKotlinModule
 import java.io.StringWriter
+import org.apache.kafka.streams.KeyValue
 import org.apache.kafka.streams.StreamsBuilder
 import org.apache.kafka.streams.Topology
 import org.apache.kafka.streams.kstream.KStream
@@ -154,6 +155,7 @@ class KafkaTopology(
                 jsonWriter.writeValue(out, value)
                 out.toString()
             }
+            .map { key, value -> KeyValue(key.substringAfterLast("/"), value) }
             .to(settings.outputTopic)
     }
 }