Ignoring unused library classes...java.io.ioexception:you has to specify '-keep ' options for the S

When you perform a Maven install package, the following error message appears:
Ignoring unused library classes...java.io.ioexception:you has to specify '-keep ' options for the shrinking step.

[Proguard] Ignoring unused library classes...java.io.ioexception:you has toSpecify'-keep 'Options for  theShrinking step.   [Proguard] Original Number  ofLibrary classes:19765[Proguard] Final Number  ofLibrary classes:19765[Proguard] Setting Target versions ...  [Proguard] [Proguard] atProguard. Seedprinter.Write(Seedprinter.java: -) [Proguard] atProguard. Proguard.printseeds (Proguard.java:265) [Proguard] atProguard. Proguard.execute (Proguard.java:108) [Proguard] Printing kept classes, fields, andMethods ... atProguard. Proguard.main (Proguard.java:538) [Proguard]

Ignore unused Library classes ... java.io.IOException: You must specify the '-hold ' option to narrow it down.

It seems that the '-keep ' option is a must for Proguard design principles, and if you want to confuse all classes, set a non-existent filter, for example:

publicclass com.abcd.* {    publicprotected *;}

Ignoring unused library classes...java.io.ioexception:you has to specify '-keep ' options for the S