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.
server/src/main/java/org/elasticsearch/TransportVersion.java
return new TransportVersion(id);
    }
    public static void writeVersion(TransportVersion version, StreamOutput out) throws IOException {
        out.writeVInt(version.id);
    }
    /**
     * Returns the minimum version of {@code version1} and {@code version2}
     */
    public static TransportVersion min(TransportVersion version1, TransportVersion version2) {
        return version1.id < version2.id ? version1 : version2;
    }
    /**
     * Returns the maximum version of {@code version1} and {@code version2}
     */
    public static TransportVersion max(TransportVersion version1, TransportVersion version2) {
        return version1.id > version2.id ? version1 : version2;
    }
    /**
     * Returns {@code true} if the specified version is compatible with this running version of Elasticsearch.
     */
    public static boolean isCompatible(TransportVersion version) {
        return version.onOrAfter(MINIMUM_COMPATIBLE);
    }
    /**
     * Reference to the most recent transport version.
     * This should be the transport version with the highest id.
     */
    public static TransportVersion current() {
        return CurrentHolder.CURRENT;