https://spring.io/projects/spring-boot: Spring Boot (Pivotal Software, Inc.) 
public interface org.springframework.boot.web.server.GracefulShutdownCallback
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.springframework.boot.web.server.GracefulShutdownCallback
  super_class: java.lang.Object
{
  public abstract void shutdownComplete(org.springframework.boot.web.server.GracefulShutdownResult);
    descriptor: (Lorg/springframework/boot/web/server/GracefulShutdownResult;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
        Name  Flags
      result  
}
SourceFile: "GracefulShutdownCallback.java"
    RuntimeVisibleAnnotations: 
      java.lang.FunctionalInterface()