fix(synchronized): suspected simultaneous access to ArrayList from multiple threads.

Author: Enuviel

AndroidSDK/src/com/leanplum/internal/LeanplumManifestHelper.java

@@ -78,7 +78,10 @@ public class LeanplumManifestHelper {
   /**
    * Gets application components from AndroidManifest.xml file.
    */
-  private static void parseManifestNodeChildren() {
+  private static synchronized void parseManifestNodeChildren() {
+    if (manifestData != null) {
+      return;
+    }
     manifestData = new ManifestData();
     byte[] manifestXml = getByteArrayOfManifest();
     Document manifestDocument = getManifestDocument(manifestXml);