code: public TemporalAccessor parseUnresolved(CharSequence text, ParsePosition position) {
          DateTimeParseContext context = parseUnresolved0(text, position);
          if (context == null) {
              return null;
          }
          return context.toUnresolved();
      }
docs: Parses the text using this formatter, without resolving the result, intended
  for advanced use cases.
  <p>
  Parsing is implemented as a two-phase operation.
  First, the text is parsed using the layout defined by the formatter, producing
  a {@code Map} of field to value, a {@code ZoneId} and a {@code Chronology}.
  Second, the parsed data is <em>resolved</em>, by validating, combining and
  simplifying the various fields into more useful ones.
  This method performs the parsing stage but not the resolving stage.
  <p>
  The result of this method is {@code TemporalAccessor} which represents the
  data as seen in the input. Values are not validated, thus parsing a date string
  of '2012-00-65' would result in a temporal with three fields - year of '2012',
  month of '0' and day-of-month of '65'.
  <p>
  The text will be parsed from the specified start {@code ParsePosition}.
  The entire length of the text does not have to be parsed, the {@code ParsePosition}
  will be updated with the index at the end of parsing.
  <p>
  Errors are returned using the error index field of the {@code ParsePosition}
  instead of {@code DateTimeParseException}.
  The returned error index will be set to an index indicative of the error.
  Callers must check for errors before using the result.
  <p>
  If the formatter parses the same field more than once with different values,
  the result will be an error.
  <p>
  This method is intended for advanced use cases that need access to the
  internal state during parsing. Typical application code should use
  {@link #parse(CharSequence, TemporalQuery)} or the parse method on the target type.
  
  @param text  the text to parse, not null
  @param position  the position to parse from, updated with length parsed
  and the index of any error, not null
  @return the parsed text, null if the parse results in an error
  @throws DateTimeException if some problem occurs during parsing
  @throws IndexOutOfBoundsException if the position is invalid