private HttpResponse updateReindexing(ApplicationId applicationId, HttpRequest request) {
        String speedValue = request.getProperty("speed");
        if (speedValue == null)
            throw new IllegalArgumentException("request must specify 'speed' parameter");

        return modifyReindexing(applicationId, request,
                                (original, cluster, type) -> original.withSpeed(cluster, type, Double.parseDouble(speedValue)),
                                new StringJoiner(", ", "Set reindexing speed to '" + speedValue + "' for document types ", " of application " + applicationId)
                                        .setEmptyValue("Changed reindexing of no document types of application " + applicationId));
    }
Operations on applications (delete, wait for config convergence, restart, application content etc.)

@author hmusum
configserver/src/main/java/com/yahoo/vespa/config/server/http/v2/ApplicationHandler.java