Fixed default return value for the drone attributes.

Author: m4gr3d

ClientLib/build.gradle

@@ -2,7 +2,7 @@ apply plugin: 'com.android.library'
 
 ext {
     PUBLISH_ARTIFACT_ID = 'dronekit-android'
-    PUBLISH_VERSION = '2.3.12'
+    PUBLISH_VERSION = '2.3.13'
     PROJECT_DESCRIPTION = "Android DroneKit client library."
     PROJECT_LABELS = ['3DR', '3DR Services', 'DroneAPI', 'Android', 'DroneKit']
     PROJECT_LICENSES = ['Apache-2.0']
@@ -17,7 +17,7 @@ android {
     defaultConfig {
         minSdkVersion 14
         targetSdkVersion 21
-        versionCode 20312
+        versionCode 20313
         versionName PUBLISH_VERSION
     }
 

ClientLib/src/main/java/com/o3dr/android/client/Drone.java

@@ -221,7 +221,7 @@ public long getFlightTime() {
 
     public <T extends Parcelable> T getAttribute(String type) {
         if (!isStarted() || type == null)
-            return null;
+            return this.getAttributeDefaultValue(type);
 
         T attribute = null;
         Bundle carrier = null;
@@ -271,6 +271,9 @@ public void run() {
     }
 
     private <T extends Parcelable> T getAttributeDefaultValue(String attributeType) {
+        if(attributeType == null)
+            return null;
+
         switch (attributeType) {
             case AttributeType.ALTITUDE:
                 return (T) new Altitude();