https://projects.eclipse.org/projects/ee4j.grizzly/grizzly-websockets-server: Grizzly Bill of Materials (BOM) (Oracle Corporation) 
public interface org.glassfish.grizzly.asyncqueue.PushBackHandler
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.glassfish.grizzly.asyncqueue.PushBackHandler
  super_class: java.lang.Object
{
  public abstract void onAccept(org.glassfish.grizzly.Connection, org.glassfish.grizzly.asyncqueue.WritableMessage);
    descriptor: (Lorg/glassfish/grizzly/Connection;Lorg/glassfish/grizzly/asyncqueue/WritableMessage;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
            Name  Flags
      connection  
      message     

  public abstract void onPushBack(org.glassfish.grizzly.Connection, org.glassfish.grizzly.asyncqueue.WritableMessage, org.glassfish.grizzly.asyncqueue.PushBackContext);
    descriptor: (Lorg/glassfish/grizzly/Connection;Lorg/glassfish/grizzly/asyncqueue/WritableMessage;Lorg/glassfish/grizzly/asyncqueue/PushBackContext;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
                 Name  Flags
      connection       
      message          
      pushBackContext  
}
SourceFile: "PushBackHandler.java"
    RuntimeVisibleAnnotations: 
      java.lang.Deprecated()