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.jce.interfaces;

import java.util.Enumeration;

import org.bouncycastle.asn1.DEREncodable;
import org.bouncycastle.asn1.DERObjectIdentifier;


allow us to set attributes on objects that can go into a PKCS12 store.

/**
 * allow us to set attributes on objects that can go into a PKCS12 store.
 */
public interface PKCS12BagAttributeCarrier
{
    void setBagAttribute(
        DERObjectIdentifier oid,
        DEREncodable        attribute);

    DEREncodable getBagAttribute(
        DERObjectIdentifier oid);

    Enumeration getBagAttributeKeys();
}