Release version with proguard issues - GSON

Question

If I build my app in debug it works perfectly. However, when I build for release with proguard, I get several errors and then the build fails. The error summary:

Warning:there were 445 unresolved references to classes or interfaces.
Warning:there were 13 instances of library classes depending on program classes.

I modified my proguard-rules.txt file as shown below. This allowed the build to succeed, but when I install the app, the amazon downloads do not work (works in the debug version).

-keep class org.xmlpull.v1.**
-keep class org.apache.http.**
-keep class org.ietf.jgss.**
-keep class com.amazonaws.services.**
-keep class org.w3c.dom.bootstrap.**

-dontwarn org.xmlpull.v1.**
-dontwarn org.apache.http.**
-dontwarn org.ietf.jgss.**
-dontwarn com.amazonaws.services.**
-dontwarn org.w3c.dom.bootstrap.**

Any suggestions as to how I can get this fixed please?

Update:

Have narrowed it down to a GSON/JSONPARSER issue. For the release version, JSONPARSER does not convert downloaded json to a supplied class like it does in debug. The GSON proguard rules (see update 2 ) have also been added but the issue persists.

-keep class org.apache.commons.logging.**               { *; }
-keep class com.amazonaws.services.sqs.QueueUrlHandler  { *; }
-keep class com.amazonaws.javax.xml.transform.sax.*     { public *; }
-keep class com.amazonaws.javax.xml.stream.**           { *; }
-keep class com.amazonaws.services.**.model.*Exception* { *; }
-keep class com.amazonaws.internal.**                   { *; }
-keep class org.codehaus.**                             { *; }
-keep class org.joda.convert.*                          { *; }
-keepattributes Signature,*Annotation*,EnclosingMethod
-keepnames class com.fasterxml.jackson.** { *; }
-keepnames class com.amazonaws.** { *; }
-dontwarn com.amazonaws.auth.policy.conditions.S3ConditionFactory
-dontwarn org.joda.time.**
-dontwarn com.fasterxml.jackson.databind.**
-dontwarn javax.xml.stream.events.**
-dontwarn org.codehaus.jackson.**
-dontwarn org.apache.commons.logging.impl.**
-dontwarn org.apache.http.conn.scheme.**
-dontwarn org.apache.http.annotation.**
-dontwarn org.ietf.jgss.**
-dontwarn org.w3c.dom.bootstrap.**

-dontwarn org.xmlpull.v1.**
-dontwarn com.amazonaws.services.**

-libraryjars libs/aws-android-sdk-1.7.1.1-core.jar
-libraryjars libs/aws-android-sdk-1.7.1.1-s3.jar
-libraryjars libs/gson-2.2.4.jar
-libraryjars libs/ksoap2-android-assembly-3.3.0-jar-with-dependencies.jar

Update 2

# Gson uses generic type information stored in a class file when working with fields. Proguard
# removes such information by default, so configure it to keep all of it.
-keepattributes Signature

# For using GSON @Expose annotation
-keepattributes *Annotation*

# Gson specific classes
-keep class sun.misc.Unsafe { *; }
-keep class com.google.gson.stream.** { *; }

# Application classes that will be serialized/deserialized over Gson
-keep class com.google.gson.examples.android.model.** { *; }

Answer 1

Finally solved. GSON could not convert my JSON into a class using the fromJson method as proguard had obfuscated my class's fields. I had to add for each of my classes used during json deserialization:

-keepclassmembers class fully.qualified.path.to.class$innerclass { 
        private <fields>; 
}

As per usual, no mention of this in the GSON docs. This was a project I took over - I personally have never used GSON and wont do so in future.

A few notes to those facing similar issues:

• Always make sure when you use a library to include all the recommended (by the library - see their web pages) entries in your proguard-rules.text file.

Answer 2

They have mentioned in the comments in the second last line of update2.

# Application classes that will be serialized/deserialized over Gson
-keep class com.google.gson.examples.android.model.** { *; }

Change the last line to your actual path inside code to classes that will be serialized. Don't copy paste as it is. Example:

-keep class com.myclass.model.** { *; }

That worked for me.