Add km module kafka gateway

clients/build/resources/main/common/message/DefaultPrincipal.json

@@ -0,0 +1,31 @@
+// Licensed to the Apache Software Foundation (ASF) under one or more
+// contributor license agreements.  See the NOTICE file distributed with
+// this work for additional information regarding copyright ownership.
+// The ASF licenses this file to You under the Apache License, Version 2.0
+// (the "License"); you may not use this file except in compliance with
+// the License.  You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+{
+  "type": "data",
+  "name": "DefaultPrincipal",
+  // The encoding format for default Kafka principal in
+  // org.apache.kafka.common.security.authenticator.DefaultKafkaPrincipalBuilder.
+  "validVersions": "0",
+  "flexibleVersions": "0+",
+  "fields": [
+    {"name": "Type", "type": "string", "versions": "0+",
+      "about": "The principal type"},
+    {"name": "Name", "type": "string", "versions": "0+",
+      "about": "The principal name"},
+    {"name": "TokenAuthenticated", "type": "bool", "versions": "0+",
+      "about": "Whether the principal was authenticated by a delegation token on the forwarding broker."}
+  ]
+}