http://www.bouncycastle.org/java.html: The Bouncy Castle Crypto package is a Java implementation of cryptographic algorithms. This jar contains JCE provider and lightweight API for the Bouncy Castle Cryptography APIs for JDK 1.5. 
public interface org.bouncycastle.jce.interfaces.ECPrivateKey extends org.bouncycastle.jce.interfaces.ECKey, java.security.PrivateKey
  minor version: 0
  major version: 59
  flags: flags: (0x0601) ACC_PUBLIC, ACC_INTERFACE, ACC_ABSTRACT
  this_class: org.bouncycastle.jce.interfaces.ECPrivateKey
  super_class: java.lang.Object
{
  public abstract java.math.BigInteger getD();
    descriptor: ()Ljava/math/BigInteger;
    flags: (0x0401) ACC_PUBLIC, ACC_ABSTRACT
}
SourceFile: "ECPrivateKey.java"