Keep class with members for retrofit annotation

Author: quangson91

libraries/proguard-square-retrofit2.pro

@@ -5,3 +5,7 @@
 -keep class retrofit2.** { *; }
 -keepattributes Signature
 -keepattributes Exceptions
+
+-keepclasseswithmembers class * {
+    @retrofit2.http.* <methods>;
+}