Update AWSIotMqttManager to respect the SDK's global time offset (#853)

* Update AWSIotMqttManager to respect the SDK's global time offset

* Chagelog update

Author: desokroshan

CHANGELOG.md

@@ -25,6 +25,9 @@
   * Amazon Comprehend
   * Amazon Kinesis Video
 
+* **AWS IoT**
+  * Fixed the timestamp used for signing requests to AWS IoT by accounting for the offset specified in `SDKGlobalConfiguration`. See [issue #814](https://github.com/aws-amplify/aws-sdk-android/issues/814)
+
 ## [Release 2.12.6](https://github.com/aws/aws-sdk-android/releases/tag/release_v2.12.6)
 
 ### Misc. Updates

aws-android-sdk-iot/src/main/java/com/amazonaws/mobileconnectors/iot/AWSIotMqttManager.java

@@ -21,6 +21,7 @@
 import android.os.Looper;
 
 import com.amazonaws.AmazonClientException;
+import com.amazonaws.SDKGlobalConfiguration;
 import com.amazonaws.auth.AWSCredentialsProvider;
 import com.amazonaws.regions.Region;
 import com.amazonaws.util.StringUtils;
@@ -795,7 +796,7 @@ public void run() {
                 try {
                     final String mqttWebSocketURL = signer.getSignedUrl(endpointWithHttpPort, 
                         clientCredentialsProvider.getCredentials(),
-                        System.currentTimeMillis());
+                        System.currentTimeMillis() - SDKGlobalConfiguration.getGlobalTimeOffset() * MILLIS_IN_ONE_SECOND);
 
                     final MqttConnectOptions options = new MqttConnectOptions();