Add protocol dto classes #5

- schema POC

src/main/java/com/github/nginate/kafka/protocol/messages/request/TopicMetadataRequest.java

@@ -0,0 +1,18 @@
+package com.github.nginate.kafka.protocol.messages.request;
+
+import com.github.nginate.kafka.protocol.messages.Request;
+import com.github.nginate.kafka.protocol.types.Type;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+import static com.github.nginate.kafka.protocol.types.TypeName.STRING;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public class TopicMetadataRequest extends Request {
+    /**
+     * The topics to produce metadata for. If empty the request will yield metadata for all topics.
+     */
+    @Type(STRING)
+    private String[] topic;
+}

src/main/java/com/github/nginate/kafka/protocol/messages/response/MetadataResponse.java

@@ -0,0 +1,61 @@
+package com.github.nginate.kafka.protocol.messages.response;
+
+import com.github.nginate.kafka.protocol.messages.Response;
+import com.github.nginate.kafka.protocol.types.Type;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+import static com.github.nginate.kafka.protocol.types.TypeName.*;
+
+@Data
+@EqualsAndHashCode(callSuper = true)
+public class MetadataResponse extends Response {
+    @Type(WRAPPER)
+    private Broker[] brokers;
+    @Type(WRAPPER)
+    private TopicMetadata[] topicMetadata;
+
+    @Data
+    public static class Broker {
+        @Type(INT32)
+        private int nodeId;
+        @Type(STRING)
+        private String host;
+        @Type(INT32)
+        private int port;
+    }
+
+    @Data
+    public static class TopicMetadata {
+        @Type(INT16)
+        private int topicErrorCode;
+        @Type(STRING)
+        private String topicName;
+        @Type(WRAPPER)
+        private PartitionMetadata[] partitionMetadata;
+
+        @Data
+        public static class PartitionMetadata {
+            @Type(INT16)
+            private int partitionErrorCode;
+            @Type(INT32)
+            private int partitionId;
+            /**
+             * The node id for the kafka broker currently acting as leader for this partition. If no leader exists
+             * because we are in the middle of a leader election this id will be -1.
+             */
+            @Type(INT32)
+            private int leader;
+            /**
+             * The set of alive nodes that currently acts as slaves for the leader for this partition.
+             */
+            @Type(INT32)
+            private int[] replicas;
+            /**
+             * The set subset of the replicas that are "caught up" to the leader
+             */
+            @Type(INT32)
+            private int[] isr;
+        }
+    }
+}

src/main/java/com/github/nginate/kafka/protocol/types/Type.java

@@ -7,5 +7,4 @@
 @Documented
 public @interface Type {
     TypeName value();
-    boolean repeatable() default false;
 }

src/main/java/com/github/nginate/kafka/protocol/types/TypeName.java

@@ -24,5 +24,9 @@ public enum TypeName {
     /**
      * Consist of a signed int32 giving a length N followed by N bytes of content. A length of -1 indicates null.
      */
-    BYTES
+    BYTES,
+    /**
+     * Used to mark utility objects, wrapping actual binary data for protocol
+     */
+    WRAPPER
 }