https://openjdk.java.net/ 
public interface java.net.http.HttpRequest$BodyPublisher extends java.util.concurrent.Flow$Publisher<java.nio.ByteBuffer>
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: java.net.http.HttpRequest$BodyPublisher
  super_class: java.lang.Object
{
  public abstract long contentLength();
    descriptor: ()J
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
}
Signature: Ljava/lang/Object;Ljava/util/concurrent/Flow$Publisher<Ljava/nio/ByteBuffer;>;
SourceFile: "HttpRequest.java"
NestHost: java.net.http.HttpRequest
InnerClasses:
  public abstract BodyPublisher = java.net.http.HttpRequest$BodyPublisher of java.net.http.HttpRequest
  public abstract Publisher = java.util.concurrent.Flow$Publisher of java.util.concurrent.Flow