d values for the attribute.</p></td><td>Yes</td></tr></tbody></table></section><h2 id=Operation>Operation</h2><section><p>Operation specifies the operations of a request.</p><table class=message-fields><thead><tr><th>Field</th><th>Type</th><th>Description</th><th>Required</th></tr></thead><tbody><tr id=Operation-hosts><td><code>hosts</code></td><td><code>string[]</code></td><td><p>Optional. A list of hosts, which matches to the &ldquo;request.host&rdquo; attribute.</p><p>If not set, any host is allowed. Mus