public static StringBuilder elapsed(long startTimeNanos, long endTimeNanos) {
        return elapsed(endTimeNanos - startTimeNanos, TimeUnit.NANOSECONDS);
    }
Creates a new {@link StringBuilder} whose content is the human-readable representation of the duration
between the specified {@code startTimeNanos} and {@code endTimeNanos}.
core/src/main/java/com/linecorp/armeria/common/util/TextFormatter.java