https://openjdk.java.net/ 
public interface sun.security.util.MessageDigestSpi2
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: sun.security.util.MessageDigestSpi2
  super_class: java.lang.Object
{
  public abstract void engineUpdate(javax.crypto.SecretKey);
    descriptor: (Ljavax/crypto/SecretKey;)V
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Exceptions:
      throws java.security.InvalidKeyException
    MethodParameters:
      Name  Flags
      key   
}
SourceFile: "MessageDigestSpi2.java"