private static Instant getInstantFromMicros(long microsSinceEpoch) {
        return Instant.EPOCH.plus(microsSinceEpoch, ChronoUnit.MICROS);
    }
Formats the given epoch time in microseconds and duration in nanos to the format
"epochMicros[elapsedNanos]" and appends it to the specified {@link StringBuilder}.
This may be useful to record high-resolution timings such as {@link ClientConnectionTimings}.
core/src/main/java/com/linecorp/armeria/common/util/TextFormatter.java