Proguard configuration for usage of Appsync with Complex Objects

**State your question**
We are using complex objects with appsync in our project.
When running obfuscated build, the automatic file upload is not working. The mutation itself will update data properly, but file is not uploaded to S3 whatsoever. No error, no exception, nothing in logs.
Not obfuscated build is working fine.

So my question is:
How to setup proguard configuration for usage of appsync with complex objects?

**Current proguard config**
```
# Class names are needed in reflection
-keepnames class com.amazonaws.**
-keepnames class com.amazon.**
# Request handlers defined in request.handlers
-keep class com.amazonaws.services.**.*Handler
# The following are referenced but aren't required to run
-dontwarn com.fasterxml.jackson.**
-dontwarn org.apache.commons.logging.**
# Android 6.0 release removes support for the Apache HTTP client
-dontwarn org.apache.http.**
# The SDK has several references of Apache HTTP client
-dontwarn com.amazonaws.http.**
-dontwarn com.amazonaws.metrics.**
-dontwarn com.amazonaws.mobile.**
```

**Environment(please complete the following information):**
- AppSync SDK Version: [e.g. 2.9.0]
- S3 SDK Version: [e.g. 2.14.2]

**Device Information (please complete the following information):**
Any device.

No repository file or test is identified. Start by reproducing an obfuscated Android build with the supplied ProGuard configuration and reviewing the AppSync complex-object upload path; the issue is done when the required configuration is identified and verified to restore S3 uploads. The AppSync and S3 SDK versions still need to be supplied.

Written by the indexing model from the issue text.