KAFKA-16881: InitialState type leaks into the Connect REST API OpenAPI spec (#16175)

Reviewers: Chris Egerton <chrise@aiven.io>

connect/runtime/src/main/java/org/apache/kafka/connect/runtime/rest/entities/CreateConnectorRequest.java

@@ -47,7 +47,7 @@ public class CreateConnectorRequest {
         return config;
     }
 
-    @JsonProperty
+    @JsonProperty("initial_state")
     public InitialState initialState() {
         return initialState;
     }