how to deal with ProGuard error?

Warning: org.mokee.internal.preference.deviceinfo.MKVersionPreference: can’t find referenced method ‘void setTitle(int)’ in program class org.mokee.internal.preference.deviceinfo.MKVersionPreference
Warning: org.mokee.internal.preference.deviceinfo.MKVersionPreference: can’t find referenced method ‘android.content.Context getContext()’ in program class org.mokee.internal.preference.deviceinfo.MKVersionPreference
Warning: org.mokee.internal.preference.deviceinfo.MKVersionPreference: can’t find referenced method ‘void setSummary(java.lang.CharSequence)’ in program class org.mokee.internal.preference.deviceinfo.MKVersionPreference
Warning: org.mokee.internal.preference.deviceinfo.MKVersionPreference: can’t find referenced class android.support.v7.preference.Preference
Warning: org.mokee.internal.preference.deviceinfo.MKVersionPreference: can’t find referenced class android.support.v7.preference.Preference
Warning: there were 105 unresolved references to classes or interfaces.
You may need to add missing library jars or update their versions.
If your code works fine without the missing classes, you can suppress
the warnings with ‘-dontwarn’ options.
(http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass)
Warning: there were 45 unresolved references to program class members.
Your input classes appear to be inconsistent.
You may need to recompile the code.
(http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedprogramclassmember)
Error: Please correct the above warnings first.

build/core/proguard.flags add -ignorewarnings