code: @Override
      public Instant convert(String value) {
          Instant converted = null;
          if (value != null) {
              try {
                  converted = Instant.from(OffsetDateTime.parse(value));
              } catch (DateTimeException dte) {
                  throw new IllegalArgumentException(dte);
              }
          }
          return converted;
      }
docs: {@inheritDoc}