>HTTP response body.</p></td></tr><tr id=DirectHttpResponse-headers><td><code>headers</code></td><td><code>map&lt;string,&nbsp;string&gt;</code></td><td><p>Optional HTTP response headers.</p></td></tr></tbody></table></section><h2 id=Duration>Duration</h2><section><p>An instance field of type Duration denotes that the expression for the field must evaluate to
<a href=#ValueType-DURATION>ValueType.DURATION</a></p><p>Objects of type Duration are also passed to the adapters during request-time for the instance