https://openjdk.java.net/ 
public interface sun.net.www.protocol.jar.URLJarFileCallBack
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: sun.net.www.protocol.jar.URLJarFileCallBack
  super_class: java.lang.Object
{
  public abstract java.util.jar.JarFile retrieve(java.net.URL);
    descriptor: (Ljava/net/URL;)Ljava/util/jar/JarFile;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Exceptions:
      throws java.io.IOException
    MethodParameters:
      Name  Flags
      url   
}
SourceFile: "URLJarFileCallBack.java"