https://openjdk.java.net/ 
public interface sun.net.www.protocol.http.AuthenticatorKeys$AuthenticatorKeyAccess
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: sun.net.www.protocol.http.AuthenticatorKeys$AuthenticatorKeyAccess
  super_class: java.lang.Object
{
  public abstract java.lang.String getKey(java.net.Authenticator);
    descriptor: (Ljava/net/Authenticator;)Ljava/lang/String;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    MethodParameters:
      Name  Flags
      a     
}
SourceFile: "AuthenticatorKeys.java"
NestHost: sun.net.www.protocol.http.AuthenticatorKeys
InnerClasses:
  public abstract AuthenticatorKeyAccess = sun.net.www.protocol.http.AuthenticatorKeys$AuthenticatorKeyAccess of sun.net.www.protocol.http.AuthenticatorKeys
    RuntimeVisibleAnnotations: 
      java.lang.FunctionalInterface()