public Timer getExecutionTimer(String streamId, String streamRuleId) {
        Timer timer = this.streamExecutionTimers.get(streamRuleId);
        if (timer == null) {
            timer = metricRegistry.timer(MetricRegistry.name(Stream.class, streamId, "StreamRule", streamRuleId, "executionTime"));
            this.streamExecutionTimers.put(streamRuleId, timer);
        }

        return timer;
    }
@Test
    public void getExecutionTimer() {
        final Timer timer = streamMetrics.getExecutionTimer("stream-id", "stream-rule-id");

        assertThat(timer).isNotNull();
        assertThat(metricRegistry.getTimers())
                .containsKey("org.graylog2.plugin.streams.Stream.stream-id.StreamRule.stream-rule-id.executionTime");
    }