code: public ColumnConfig setDefaultValueDate(String defaultValueDate) {
          defaultValueDate = StringUtil.trimToNull(defaultValueDate);
          if ((defaultValueDate == null) || "null".equalsIgnoreCase(defaultValueDate)) {
              this.defaultValueDate = null;
          } else {
              try {
                  this.defaultValueDate = new ISODateFormat().parse(defaultValueDate);
              } catch (ParseException e) {
                  //probably a computed date
                  this.defaultValueComputed = new DatabaseFunction(defaultValueDate);
              }
          }
  
          return this;
      }
docs: Set the date this column should default to. Supports any of the date or datetime formats handled by {@link ISODateFormat}.
  If the passed value cannot be parsed as a date, it is assumed to be a function that returns a date.
  If the string "null" or an empty string is passed, it will set a null value.