What about proguard?

I have this issues:
```

com.github.davidmoten.rx.Serialized: can't find referenced class com.esotericsoftware.kryo.Kryo |  
-- | --

com.github.davidmoten.rx.Serialized: can't find referenced class com.esotericsoftware.kryo.Kryo |  
-- | --
com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.Kryo |  
com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.io.Output |  
com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.io.Input |  
com.github.davidmoten.rx.Serialized$KryoBuilder: can't find referenced class com.esotericsoftware.kryo.Kryo |  
com.github.davidmoten.rx.Serialized$KryoBuilder$1: can't find referenced class com.esotericsoftware.kryo.io.Output |  
com.github.davidmoten.rx.Serialized$KryoBuilder$2: can't find referenced class com.esotericsoftware.kryo.io.Output |  
com.github.davidmoten.rx.Serialized$KryoBuilder$2$1: can't find referenced class com.esotericsoftware.kryo.Kryo |  
com.github.davidmoten.rx.Serialized$KryoBuilder$2$1: can't find referenced class com.esotericsoftware.kryo.io.Output |  
com.github.davidmoten.rx.Serialized$KryoBuilder$3: can't find referenced class com.esotericsoftware.kryo.io.Output |  
com.github.davidmoten.rx.Serialized$KryoBuilder$4: can't find referenced class com.esotericsoftware.kryo.io.Input |  
com.github.davidmoten.rx.Serialized$KryoBuilder$5: can't find referenced class com.esotericsoftware.kryo.io.Input |  
com.github.davidmoten.rx.Serialized$KryoBuilder$6: can't find referenced class com.esotericsoftware.kryo.io.Input |  
com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.io.Input |  
com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.Kryo |  
com.github.davidmoten.rx.Serialized$KryoBuilder$7: can't find referenced class com.esotericsoftware.kryo.io.Input |  
com.github.davidmoten.rx.testing.TestSubscriber2: can't find referenced class org.junit.Assert |  
com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite$SuiteClasses |  
com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite |  
com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runner.RunWith |  
com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite |  
com.github.davidmoten.rx.testing.TestingHelper$TestSuiteFromCases: can't find referenced class org.junit.runners.Suite$SuiteClasses |  

```