Add protocol dto classes #5

- partial sync group API

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

@@ -0,0 +1,41 @@
+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.Builder;
+import lombok.Data;
+import lombok.EqualsAndHashCode;
+
+import static com.github.nginate.kafka.protocol.types.TypeName.*;
+
+/**
+ * The sync group request is used by the leader to assign state (e.g. partition assignments) to all members of the
+ * current generation. All members send SyncGroup immediately after joining the group, but only the leader provides the
+ * group's assignment.
+ * Once the group members have been stabilized by the completion of phase 1, the active leader must propagate state to
+ * the other members in the group. This is used in the new consumer protocol to set partition assignments. Similar to
+ * phase 1, all members send SyncGroup requests to the coordinator. Once group state has been provided by the leader,
+ * the coordinator forwards each member's state respectively in the SyncGroup response.
+ */
+@Data
+@Builder
+//@ApiKey(ApiKeys.) FIXME
+@EqualsAndHashCode(callSuper = true)
+public class SyncGroupRequest extends Request {
+    @Type(STRING)
+    private String groupId;
+    @Type(INT32)
+    private Integer generationId;
+    @Type(STRING)
+    private String memberId;
+    @Type(WRAPPER)
+    private GroupAssignment[] groupAssignments;
+
+    @Data
+    public static class GroupAssignment {
+        @Type(STRING)
+        private String memberId;
+        @Type(BYTES)
+        private byte[] memberAssignment;
+    }
+}

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

@@ -0,0 +1,22 @@
+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.BYTES;
+import static com.github.nginate.kafka.protocol.types.TypeName.INT16;
+
+/**
+ * Each member in the group will receive an assignment from the leader in the sync group response.
+ */
+@Data
+//@ApiKey(ApiKeys.) FIXME
+@EqualsAndHashCode(callSuper = true)
+public class SyncGroupResponse extends Response {
+    @Type(INT16)
+    private Short errorCode;
+    @Type(BYTES)
+    private byte[] memberAssignment;
+}