private static long getStartTimeOfPreviousYear(long currentEmitTime) {
        ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(Instant.ofEpochMilli(currentEmitTime),
                ZoneId.of("GMT"));
        int givenYear = zonedDateTime.getYear();
        return ZonedDateTime.of(--givenYear, 1, 1, 0, 0, 0, 0, ZoneId.of("GMT"))
                .toEpochSecond() * 1000;
    }
Performs time conversions related to incremental aggregation.
modules/siddhi-core/src/main/java/io/siddhi/core/util/IncrementalTimeConverterUtil.java