Extra protection from null values

common/data/src/main/java/org/thingsboard/server/common/data/StringUtils.java

@@ -46,6 +46,10 @@ public class StringUtils {
         return source != null && !source.isEmpty() && !source.trim().isEmpty();
     }
 
+    public static String notBlankOrDefault(String src, String def) {
+        return isNotBlank(src) ? src : def;
+    }
+
     public static String removeStart(final String str, final String remove) {
         if (isEmpty(str) || isEmpty(remove)) {
             return str;

common/data/src/main/java/org/thingsboard/server/common/data/device/profile/MqttDeviceProfileTransportConfiguration.java

@@ -17,8 +17,10 @@ package org.thingsboard.server.common.data.device.profile;
 
 import lombok.Data;
 import org.thingsboard.server.common.data.DeviceTransportType;
+import org.thingsboard.server.common.data.StringUtils;
 import org.thingsboard.server.common.data.validation.NoXss;
 
+import java.util.Objects;
 import java.util.Set;
 
 @Data
@@ -42,12 +44,19 @@ public class MqttDeviceProfileTransportConfiguration implements DeviceProfileTra
     }
 
     public TransportPayloadTypeConfiguration getTransportPayloadTypeConfiguration() {
-        if (transportPayloadTypeConfiguration != null) {
-            return transportPayloadTypeConfiguration;
-        } else {
-            return new JsonTransportPayloadConfiguration();
-        }
+        return Objects.requireNonNullElseGet(transportPayloadTypeConfiguration, JsonTransportPayloadConfiguration::new);
     }
 
+    public String getDeviceTelemetryTopic() {
+        return StringUtils.notBlankOrDefault(deviceTelemetryTopic, MqttTopics.DEVICE_TELEMETRY_TOPIC);
+    }
+
+    public String getDeviceAttributesTopic() {
+        return StringUtils.notBlankOrDefault(deviceAttributesTopic, MqttTopics.DEVICE_ATTRIBUTES_TOPIC);
+    }
+
+    public String getDeviceAttributesSubscribeTopic() {
+        return StringUtils.notBlankOrDefault(deviceAttributesSubscribeTopic, MqttTopics.DEVICE_ATTRIBUTES_TOPIC);
+    }
 
 }