in ecs-logging-core/src/main/java/co/elastic/logging/TimestampSerializer.java [67:96]
void serializeEpochTimestampAsIsoDateTime(StringBuilder builder, long epochTimestamp) {
CachedDate cachedDateLocal = cachedDate;
if (cachedDateLocal == null || !cachedDateLocal.isDateCached(epochTimestamp)) {
cachedDate = cachedDateLocal = new CachedDate(epochTimestamp);
}
builder.append(cachedDateLocal.getCachedDateIso());
builder.append(TIME_SEPARATOR);
// hours
long remainder = epochTimestamp % MILLIS_PER_DAY;
serializeWithLeadingZero(builder, remainder / MILLIS_PER_HOUR, 2);
builder.append(COLON);
// minutes
remainder %= MILLIS_PER_HOUR;
serializeWithLeadingZero(builder, remainder / MILLIS_PER_MINUTE, 2);
builder.append(COLON);
// seconds
remainder %= MILLIS_PER_MINUTE;
serializeWithLeadingZero(builder, remainder / MILLIS_PER_SECOND, 2);
builder.append(DOT);
// milliseconds
remainder %= MILLIS_PER_SECOND;
serializeWithLeadingZero(builder, remainder, 3);
builder.append(TIME_ZONE_SEPARATOR);
}