private static String createConfigJson(DashboardConfiguration dashboardConfiguration) throws IOException {
	StringWriter writer = new StringWriter();
	JsonGenerator gen = JsonFactory.JACKSON_FACTORY.createGenerator(writer);

	gen.writeStartObject();
	gen.writeNumberField(DashboardConfiguration.FIELD_NAME_REFRESH_INTERVAL, dashboardConfiguration.getRefreshInterval());
	gen.writeNumberField(DashboardConfiguration.FIELD_NAME_TIMEZONE_OFFSET, dashboardConfiguration.getTimeZoneOffset());
	gen.writeStringField(DashboardConfiguration.FIELD_NAME_TIMEZONE_NAME, dashboardConfiguration.getTimeZoneName());
	gen.writeStringField(DashboardConfiguration.FIELD_NAME_FLINK_VERSION, dashboardConfiguration.getFlinkVersion());
	gen.writeStringField(DashboardConfiguration.FIELD_NAME_FLINK_REVISION, dashboardConfiguration.getFlinkRevision());

	gen.writeEndObject();

	gen.close();

	return writer.toString();
}
 

private static String createConfigJson(DashboardConfiguration dashboardConfiguration) throws IOException {
	StringWriter writer = new StringWriter();
	JsonGenerator gen = JsonFactory.JACKSON_FACTORY.createGenerator(writer);

	gen.writeStartObject();
	gen.writeNumberField(DashboardConfiguration.FIELD_NAME_REFRESH_INTERVAL, dashboardConfiguration.getRefreshInterval());
	gen.writeNumberField(DashboardConfiguration.FIELD_NAME_TIMEZONE_OFFSET, dashboardConfiguration.getTimeZoneOffset());
	gen.writeStringField(DashboardConfiguration.FIELD_NAME_TIMEZONE_NAME, dashboardConfiguration.getTimeZoneName());
	gen.writeStringField(DashboardConfiguration.FIELD_NAME_FLINK_VERSION, dashboardConfiguration.getFlinkVersion());
	gen.writeStringField(DashboardConfiguration.FIELD_NAME_FLINK_REVISION, dashboardConfiguration.getFlinkRevision());

	gen.writeEndObject();

	gen.close();

	return writer.toString();
}
 

private void createDashboardConfigFile() throws IOException {
	try (FileWriter fw = createOrGetFile(webDir, "config")) {
		fw.write(createConfigJson(DashboardConfiguration.from(webRefreshIntervalMillis, ZonedDateTime.now())));
		fw.flush();
	} catch (IOException ioe) {
		LOG.error("Failed to write config file.");
		throw ioe;
	}
}
 

public DashboardConfigHandler(
		GatewayRetriever<? extends RestfulGateway> leaderRetriever,
		Time timeout,
		Map<String, String> responseHeaders,
		MessageHeaders<EmptyRequestBody, DashboardConfiguration, EmptyMessageParameters> messageHeaders,
		long refreshInterval) {
	super(leaderRetriever, timeout, responseHeaders, messageHeaders);

	dashboardConfiguration = DashboardConfiguration.from(refreshInterval, ZonedDateTime.now());
}
 

private void createDashboardConfigFile() throws IOException {
	try (FileWriter fw = createOrGetFile(webDir, "config")) {
		fw.write(createConfigJson(DashboardConfiguration.from(webRefreshIntervalMillis, ZonedDateTime.now())));
		fw.flush();
	} catch (IOException ioe) {
		LOG.error("Failed to write config file.");
		throw ioe;
	}
}
 

public DashboardConfigHandler(
		GatewayRetriever<? extends RestfulGateway> leaderRetriever,
		Time timeout,
		Map<String, String> responseHeaders,
		MessageHeaders<EmptyRequestBody, DashboardConfiguration, EmptyMessageParameters> messageHeaders,
		long refreshInterval) {
	super(leaderRetriever, timeout, responseHeaders, messageHeaders);

	dashboardConfiguration = DashboardConfiguration.from(refreshInterval, ZonedDateTime.now());
}
 

private void createDashboardConfigFile() throws IOException {
	try (FileWriter fw = createOrGetFile(webDir, "config")) {
		fw.write(createConfigJson(DashboardConfiguration.from(webRefreshIntervalMillis, ZonedDateTime.now(), false)));
		fw.flush();
	} catch (IOException ioe) {
		LOG.error("Failed to write config file.");
		throw ioe;
	}
}
 

public DashboardConfigHandler(
		GatewayRetriever<? extends RestfulGateway> leaderRetriever,
		Time timeout,
		Map<String, String> responseHeaders,
		MessageHeaders<EmptyRequestBody, DashboardConfiguration, EmptyMessageParameters> messageHeaders,
		long refreshInterval,
		boolean webSubmitEnabled) {
	super(leaderRetriever, timeout, responseHeaders, messageHeaders);

	dashboardConfiguration = DashboardConfiguration.from(refreshInterval, ZonedDateTime.now(), webSubmitEnabled);
}
 

@Override
public CompletableFuture<DashboardConfiguration> handleRequest(@Nonnull HandlerRequest<EmptyRequestBody, EmptyMessageParameters> request, @Nonnull RestfulGateway gateway) {
	return CompletableFuture.completedFuture(dashboardConfiguration);
}
 

@Override
public CompletableFuture<DashboardConfiguration> handleRequest(@Nonnull HandlerRequest<EmptyRequestBody, EmptyMessageParameters> request, @Nonnull RestfulGateway gateway) {
	return CompletableFuture.completedFuture(dashboardConfiguration);
}
 

private static String createConfigJson(DashboardConfiguration dashboardConfiguration) throws IOException {
	return OBJECT_MAPPER.writeValueAsString(dashboardConfiguration);
}
 

private static DashboardConfiguration getDashboardConfiguration(String baseUrl) throws Exception {
	Tuple2<Integer, String> response = getFromHTTP(baseUrl + DashboardConfigurationHeaders.INSTANCE.getTargetRestEndpointURL());
	return OBJECT_MAPPER.readValue(response.f1, DashboardConfiguration.class);

}
 

@Override
public CompletableFuture<DashboardConfiguration> handleRequest(@Nonnull HandlerRequest<EmptyRequestBody, EmptyMessageParameters> request, @Nonnull RestfulGateway gateway) {
	return CompletableFuture.completedFuture(dashboardConfiguration);
}