bject</b> - created by using a property of each message to determine the key under which
        the required value is stored.</li>
        <li>a <b>merged object</b> - created by merging the property of each message under a single object.</li>
    </ul>
    <p>The other properties of the output message are taken from the last message received before the result is sent.</p>
    <p>A <i>count</i> can be set for how many messages should be received before generating the output message.
    For object outputs,