Add Proguard rules to fix --release bug

android/build.gradle

@@ -27,6 +27,7 @@ android {
     defaultConfig {
         minSdkVersion 16
         testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
+        consumerProguardFiles 'proguard-rules.pro'
     }
     lintOptions {
         disable 'InvalidPackage'

android/proguard-rules.pro

@@ -0,0 +1,18 @@
+# Add project specific ProGuard rules here.
+# By default, the flags in this file are appended to flags specified
+# in C:\Program Files (x86)\Android\sdk/tools/proguard/proguard-android.txt
+# You can edit the include path and order by changing the proguardFiles
+# directive in build.gradle.
+#
+# For more details, see
+#   http://developer.android.com/guide/developing/tools/proguard.html
+# Add any project specific keep options here:
+-keep class com.onesignal.** { *; }
+-dontwarn com.onesignal.**
+
+# If your project uses WebView with JS, uncomment the following
+# and specify the fully qualified class name to the JavaScript interface
+# class:
+#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
+#   public *;
+#}