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. 
package org.bouncycastle.asn1;

import java.io.IOException;


A NULL object.

/**
 * A NULL object.
 */
public class DERNull
    extends ASN1Null
{
    public static final DERNull INSTANCE = new DERNull();

    byte[]  zeroBytes = new byte[0];

    public DERNull()
    {
    }

    void encode(
        DEROutputStream  out)
        throws IOException
    {
        out.writeEncoded(NULL, zeroBytes);
    }
}