Getting crash while running with proguard enabled in android application

Hi,
Are there any predefined set of rules. I am getting crash when we are launching the application in release mode

11-26 18:17:19.506 5386-5386/com.radaee.reader A/art: art/runtime/java_vm_ext.cc:410] JNI DETECTED ERROR IN APPLICATION: JNI CallBooleanMethodV called with pending exception java.lang.NoSuchMethodError: no non-static method "Lcom/radaee/util/f;.writeable()Z"
11-26 18:17:19.506 5386-5386/com.radaee.reader A/art: art/runtime/java_vm_ext.cc:410] at long com.radaee.pdf.Document.openStream(com.radaee.pdf.Document$f, java.lang.String) (SourceFile:-2)
11-26 18:17:19.506 5386-5386/com.radaee.reader A/art: art/runtime/java_vm_ext.cc:410] at int com.radaee.pdf.Document.a(com.radaee.pdf.Document$f, java.lang.String) (SourceFile:10)

dear user:
i guess you are using PDFHttpStream or PDFMemStream, and methods of PDFHttpStream or PDFMemStream renamed as random name.
so, i suggest you do not proguard on package:
com.radaee.pdf
com.radaee.util