https://openjdk.java.net/ 
public interface java.security.interfaces.XECPrivateKey extends java.security.interfaces.XECKey, java.security.PrivateKey
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: java.security.interfaces.XECPrivateKey
  super_class: java.lang.Object
{
  public abstract java.util.Optional<byte[]> getScalar();
    descriptor: ()Ljava/util/Optional;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
    Signature: ()Ljava/util/Optional<[B>;
}
SourceFile: "XECPrivateKey.java"