This figure consists of a cylinder labeled Provider C and a box. Dotted lines are used to indicate that Provider C contains the contents of the box. The box contains the following headers and Java code:
provider.java   public class fooJCA extends Provider {
    .
    .
    .
    put("MessageDigest.SHA-256", "com.foo.SHA256");
    .
    .
    .
{}com.foo.SHA256.java    package com.foo;
public class SHA256 extends
MessageDigestSpi {
   .
   .
   .
}