async fn describe_agent_versions(
        &self,
        input: DescribeAgentVersionsRequest,
    ) -> Result<DescribeAgentVersionsResult, RusotoError<DescribeAgentVersionsError>> {
        let mut request = self.new_signed_request("POST", "/");
        request.add_header("x-amz-target", "OpsWorks_20130218.DescribeAgentVersions");
        let encoded = serde_json::to_string(&input).unwrap();
        request.set_payload(Some(encoded));

        let response = self
            .sign_and_dispatch(request, DescribeAgentVersionsError::from_response)
            .await?;
        let mut response = response;
        let response = response.buffer().await.map_err(RusotoError::HttpDispatch)?;
        proto::json::ResponsePayload::new(&response).deserialize::<DescribeAgentVersionsResult, _>()
    }
<p>Describes the available AWS OpsWorks Stacks agent versions. You must specify a stack ID or a configuration manager. <code>DescribeAgentVersions</code> returns a list of available agent versions for the specified stack or configuration manager.</p>
rusoto/services/opsworks/src/generated.rs