proguard: handle JsonObjectMapper for abstract classes
proguard: handle JsonObjectMapper for abstract classes

orz3969/LoganSquare,bunnyblue/LoganSquare,Hobbit-Nova/LoganSquare,luoxiaoshenghustedu/LoganSquare,tsdl2013/LoganSquare,wayne4106/LoganSquare,nguyenhongson03/LoganSquare,aaaliua/LoganSquare,jtyang/LoganSquare,yungfan/LoganSquare,bluelinelabs/LoganSquare,sangupandi/LoganSquare,Meowzm/LoganSquare,3bdoelnaggar/LoganSquare,ranjith068/LoganSquare,aurae/LoganSquare,fengchenlianlian/LoganSquare,ppamorim/LoganSquare,honeyflyfish/LoganSquare,oeager/LoganSquare