https://openjdk.java.net/ 
public interface java.util.prefs.PreferencesFactory
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: java.util.prefs.PreferencesFactory
  super_class: java.lang.Object
{
  public abstract java.util.prefs.Preferences systemRoot();
    descriptor: ()Ljava/util/prefs/Preferences;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT

  public abstract java.util.prefs.Preferences userRoot();
    descriptor: ()Ljava/util/prefs/Preferences;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
}
SourceFile: "PreferencesFactory.java"