Proguard rule update.

app/proguard-rules.pro

@@ -14,18 +14,16 @@
 
 # Uncomment this to preserve the line number information for
 # debugging stack traces.
--keepattributes SourceFile,LineNumberTable
+-keepattributes SourceFile,LineNumberTable        # Keep file names and line numbers.
+-keep public class * extends java.lang.Exception  # Optional: Keep custom exceptions.
 
 # If you keep the line number information, uncomment this to
 # hide the original source file name.
 -renamesourcefileattribute SourceFile
 
 # For SerializedName
-
 -keepattributes *Annotation*
-
 -keepclassmembers,allowobfuscation class * {
   @com.google.gson.annotations.SerializedName <fields>;
 }
-
 -keep,allowobfuscation @interface com.google.gson.annotations.SerializedName