## Documenting the callback

The actual callback code will depend heavily on your own API app.

And it will probably vary a lot from one app to the next.

It could be just one or two lines of code, like:

```Python
callback_url = "https://example.com/api/v1/invoices/events/"

 * instantiated. Similar to <code>System</code> properties the namespace
 * is global therefore property names should be unique. Before use,
 * the <code>load</code> method should be called with the name of a
 * <code>Properties</code> file (or <code>null</code> indicating no
 * file) to initialize the <code>Config</code>. The <code>System</code>
 * properties will then populate the <code>Config</code> as well potentially

 * </code></td><td width="20%"><code>
 *  ../.././.././../foo/
 * </code></td><td><code>
 *  smb1://host/foo/
 * </code></td></tr>
 * 
 * <tr><td width="20%"><code>
 *  smb1://host/share/zig/zag
 * </code></td><td width="20%"><code>
 *  /
 * </code></td><td><code>
 *  smb1://host/
 * </code></td></tr>
 * 
 * <tr><td width="20%"><code>
 *  smb1://server/
 * </code></td><td width="20%"><code>
 *  ../

   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
   * code would be responsible for populating a "real" {@code T} (which might still be the value

import javax.annotation.CheckForNull;

/**
 * A map containing {@code long} values that can be atomically updated. While writes to a
 * traditional {@code Map} rely on {@code put(K, V)}, the typical mechanism for writing to this map
 * is {@code addAndGet(K, long)}, which adds a {@code long} to the value currently associated with
 * {@code K}. If a key has not yet been associated with a value, its implicit value is zero.
 *

   * its runtime check.
   *
   * <p>An example use case for this method is in implementing an {@code Iterator<T>} whose {@code
   * next} field is lazily initialized. The type of that field would be {@code @Nullable T}, and the
   * code would be responsible for populating a "real" {@code T} (which might still be the value

     * value is undefined.
     *
     * @return The location of the problem, never {@code null}.
     */
    String getLocation();

    /**
     * Gets the exception that caused this problem (if any).
     *
     * @return The exception that caused this problem or {@code null} if not applicable.
     */
    Exception getException();

    /**

    resetContainer(getSubjectGenerator().create(array));
  }

  /**
   * Equivalent to {@link #expectMissing(Object[]) expectMissing}{@code (null)} except that the call
   * to {@code contains(null)} is permitted to throw a {@code NullPointerException}.
   *
   * @param message message to use upon assertion failure
   */
  protected void expectNullMissingWhenNullUnsupported(String message) {
    try {

/**
 * パラメタ化されたクラスを扱うためのインターフェースです。
 *
 * @author koichik
 */
public interface ParameterizedClassDesc {

    /**
     * このインスタンスが表現するクラスがパラメタ化されていれば<code>true</code>を返します。
     *
     * @return このインスタンスが表現するクラスがパラメタ化されていれば<code>true</code>
     */
    boolean isParameterizedClass();

    /**
     * 原型となるクラスを返します。
     *
     * @param <T>
     *            原型となるクラスの型
     * @return 原型となるクラス

 * supplied by the user of the class. For example, {@code Multiset.Entry.getElement()} returns
 * {@code @ParametricNullness E}, which means:
 *
 * <ul>
 *   <li>{@code getElement} on a {@code Multiset.Entry<@NonNull String>} returns {@code @NonNull
 *       String}.
 *   <li>{@code getElement} on a {@code Multiset.Entry<@Nullable String>} returns {@code @Nullable
 *       String}.
 * </ul>
 *