src/java.base/share/classes/java/time/format/DateTimeFormatter.java

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  import java.text.ParsePosition;
  import java.time.DateTimeException;
  import java.time.Period;
  import java.time.ZoneId;
  import java.time.ZoneOffset;
+ import java.time.chrono.ChronoLocalDateTime;
  import java.time.chrono.Chronology;
  import java.time.chrono.IsoChronology;
  import java.time.format.DateTimeFormatterBuilder.CompositePrinterParser;
  import java.time.temporal.ChronoField;
  import java.time.temporal.IsoFields;
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   * date and/or time that was resolved. Thus, an earlier stage would resolve
   * (year + month + day-of-month) to a date, and this stage would check that
   * day-of-week was valid for the date.
   * <li>If an {@linkplain #parsedExcessDays() excess number of days}
   * was parsed then it is added to the date if a date is available.
+  * <li> If a second-based field is present, but {@code LocalTime} was not parsed,
+  * then the resolver ensures that milli, micro and nano second values are
+  * available to meet the contract of {@link ChronoField}.
+  * These will be set to zero if missing.
+  * <li>If both date and time were parsed and either an offset or zone is present,
+  * the field {@link ChronoField#INSTANT_SECONDS} is created.
+  * If an offset was parsed then the offset will be combined with the
+  * {@code LocalDateTime} to form the instant, with any zone ignored.
+  * If a {@code ZoneId} was parsed without an offset then the zone will be 
+  * combined with the {@code LocalDateTime} to form the instant using the rules
+  * of {@link ChronoLocalDateTime#atZone(ZoneId)}.
   * </ol>
   *
   * @implSpec
   * This class is immutable and thread-safe.
   *