.map(String::trim)
                .filter(s -> !requiredValidator.isValid(source.get(s), null))
                .collect(Collectors.toList()));
    }

    default boolean isNonEmptyValue(final Object value) {
        final RequiredValidator requiredValidator = new RequiredValidator();
        return requiredValidator.isValid(value, null);
    }

    String getCrawlerDocumentSpaceChars();

                start = moment(this.element.val(), this.locale.format);
                end = start;
            }

            if (!start.isValid() || !end.isValid()) return;

            this.setStartDate(start);
            this.setEndDate(end);
            this.updateView();
        },

        keydown: function(e) {