presto-main/src/main/java/io/prestosql/util/JsonUtil.java/JsonUtil/writeJsonValue
class JsonUtil:        @Override
        public void writeJsonValue(JsonGenerator jsonGenerator, Block block, int position, ConnectorSession session)
                throws IOException
        {
            if (block.isNull(position)) {
                jsonGenerator.writeNull();
            }
            else {
                long value = TIMESTAMP.getLong(block, position);
                jsonGenerator.writeString(printTimestampWithoutTimeZone(session.getTimeZoneKey(), value));
            }
        }