https://openjdk.java.net/ 
interface sun.nio.ch.Cancellable
  minor version: 0
  major version: 59
  flags: flags: (0x0600) ACC_INTERFACE, ACC_ABSTRACT
  this_class: sun.nio.ch.Cancellable
  super_class: java.lang.Object
{
  public abstract void onCancel(sun.nio.ch.PendingFuture<?, ?>);
    descriptor: (Lsun/nio/ch/PendingFuture;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: (Lsun/nio/ch/PendingFuture<**>;)V
    MethodParameters:
      Name  Flags
      task  
}
SourceFile: "Cancellable.java"