Currently when using `unit` parameter in the `rate` aggregator in time series mode (meaning the `rate` aggregation is defined as a child aggregation of `time_series` aggregation) then this parameter is ignored. We should investigate whether this parameter can be supported for computing rate in time series mode.
x-pack/plugin/analytics/src/test/java/org/elasticsearch/xpack/analytics/rate/InternalResetTrackingRateTests.java
@Override
    protected void assertFromXContent(InternalResetTrackingRate aggregation, ParsedAggregation parsedAggregation) throws IOException {
    }
    @Override
    protected List<NamedXContentRegistry.Entry> getNamedXContents() {
        return CollectionUtils.appendToCopy(
            super.getNamedXContents(),
            new NamedXContentRegistry.Entry(Aggregation.class, new ParseField(InternalResetTrackingRate.NAME), (p, c) -> {
                assumeTrue("There is no ParsedRate yet", false);
                return null;
            })
        );
    }
    public void testIncludes() {
        InternalResetTrackingRate big = new InternalResetTrackingRate("n", null, null, 0, 0, 1000, 3000, 0);
        InternalResetTrackingRate small = new InternalResetTrackingRate("n", null, null, 0, 0, 1500, 2500, 0);
        assertTrue(big.includes(small));
        assertFalse(small.includes(big));
        InternalResetTrackingRate unrelated = new InternalResetTrackingRate("n", null, null, 0, 0, 100000, 1000010, 0);
        assertFalse(big.includes(unrelated));
        assertFalse(unrelated.includes(big));
        assertFalse(small.includes(unrelated));
        assertFalse(unrelated.includes(small));
    }
    @Override
    protected InternalResetTrackingRate mutateInstance(InternalResetTrackingRate instance) {
        return null;
    }
}