Ability to fetch multiple device attributes using Gateway MQTT API

@@ -16,6 +16,7 @@
 package org.thingsboard.server.transport.mqtt.session;
 
 import com.google.gson.Gson;
+import com.google.gson.JsonArray;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import io.netty.buffer.ByteBuf;
@@ -24,6 +25,7 @@ import io.netty.buffer.UnpooledByteBufAllocator;
 import io.netty.handler.codec.mqtt.*;
 import org.thingsboard.server.common.data.Device;
 import org.thingsboard.server.common.data.id.SessionId;
+import org.thingsboard.server.common.data.kv.AttributeKvEntry;
 import org.thingsboard.server.common.data.kv.KvEntry;
 import org.thingsboard.server.common.msg.core.*;
 import org.thingsboard.server.common.msg.kv.AttributesKVMsg;
@@ -35,6 +37,7 @@ import org.thingsboard.server.transport.mqtt.MqttTopics;
 import org.thingsboard.server.transport.mqtt.MqttTransportHandler;
 
 import java.nio.charset.Charset;
+import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicInteger;
 
@@ -135,40 +138,43 @@ public class GatewayDeviceSessionCtx extends DeviceAwareSessionContext {
         if (responseData.isPresent()) {
             AttributesKVMsg msg = responseData.get();
             if (msg.getClientAttributes() != null) {
-                msg.getClientAttributes().forEach(v -> addValueToJson(result, "value", v));
+                addValues(result, msg.getClientAttributes());
             }
             if (msg.getSharedAttributes() != null) {
-                msg.getSharedAttributes().forEach(v -> addValueToJson(result, "value", v));
+                addValues(result, msg.getSharedAttributes());
             }
         }
         return createMqttPublishMsg(topic, result);
     }
 
+    private void addValues(JsonObject result, List<AttributeKvEntry> kvList) {
+        if (kvList.size() == 1) {
+            addValueToJson(result, "value", kvList.get(0));
+        } else {
+            JsonObject values;
+            if (result.has("values")) {
+                values = result.get("values").getAsJsonObject();
+            } else {
+                values = new JsonObject();
+                result.add("values", values);
+            }
+            kvList.forEach(value -> addValueToJson(values, value.getKey(), value));
+        }
+    }
+
     private void addValueToJson(JsonObject json, String name, KvEntry entry) {
         switch (entry.getDataType()) {
             case BOOLEAN:
-                Optional<Boolean> booleanValue = entry.getBooleanValue();
-                if (booleanValue.isPresent()) {
-                    json.addProperty(name, booleanValue.get());
-                }
+                entry.getBooleanValue().ifPresent(aBoolean -> json.addProperty(name, aBoolean));
                 break;
             case STRING:
-                Optional<String> stringValue = entry.getStrValue();
-                if (stringValue.isPresent()) {
-                    json.addProperty(name, stringValue.get());
-                }
+                entry.getStrValue().ifPresent(aString -> json.addProperty(name, aString));
                 break;
             case DOUBLE:
-                Optional<Double> doubleValue = entry.getDoubleValue();
-                if (doubleValue.isPresent()) {
-                    json.addProperty(name, doubleValue.get());
-                }
+                entry.getDoubleValue().ifPresent(aDouble -> json.addProperty(name, aDouble));
                 break;
             case LONG:
-                Optional<Long> longValue = entry.getLongValue();
-                if (longValue.isPresent()) {
-                    json.addProperty(name, longValue.get());
-                }
+                entry.getLongValue().ifPresent(aLong -> json.addProperty(name, aLong));
                 break;
         }
     }

@@ -41,10 +41,7 @@ import org.thingsboard.server.dao.relation.RelationService;
 import org.thingsboard.server.transport.mqtt.MqttTransportHandler;
 import org.thingsboard.server.transport.mqtt.adaptors.JsonMqttAdaptor;
 
-import java.util.Collections;
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Optional;
+import java.util.*;
 import java.util.stream.Collectors;
 
 import static org.thingsboard.server.transport.mqtt.adaptors.JsonMqttAdaptor.validateJsonPayload;
@@ -193,13 +190,22 @@ public class GatewaySessionCtx {
             int requestId = jsonObj.get("id").getAsInt();
             String deviceName = jsonObj.get(DEVICE_PROPERTY).getAsString();
             boolean clientScope = jsonObj.get("client").getAsBoolean();
-            String key = jsonObj.get("key").getAsString();
+            Set<String> keys;
+            if (jsonObj.has("key")) {
+                keys = Collections.singleton(jsonObj.get("key").getAsString());
+            } else {
+                JsonArray keysArray = jsonObj.get("keys").getAsJsonArray();
+                keys = new HashSet<>();
+                for (JsonElement keyObj : keysArray) {
+                    keys.add(keyObj.getAsString());
+                }
+            }
 
             BasicGetAttributesRequest request;
             if (clientScope) {
-                request = new BasicGetAttributesRequest(requestId, Collections.singleton(key), null);
+                request = new BasicGetAttributesRequest(requestId, keys, null);
             } else {
-                request = new BasicGetAttributesRequest(requestId, null, Collections.singleton(key));
+                request = new BasicGetAttributesRequest(requestId, null, keys);
             }
             GatewayDeviceSessionCtx deviceSessionCtx = devices.get(deviceName);
             processor.process(new BasicToDeviceActorSessionMsg(deviceSessionCtx.getDevice(),
@@ -251,7 +257,7 @@ public class GatewaySessionCtx {
     }
 
     private void ack(MqttPublishMessage msg) {
-        if(msg.variableHeader().messageId() > 0) {
+        if (msg.variableHeader().messageId() > 0) {
             writeAndFlush(MqttTransportHandler.createMqttPubAckMsg(msg.variableHeader().messageId()));
         }
     }