DateField loses readOnly property after page refresh


I’ve created a Table that uses BeanItemContainer and custom TableFieldFactory.

TableFieldFactory has one main task - make dates in table read-only and set proper resolution:

public class CustomFieldFactory extends DefaultFieldFactory {
    public Field<?> createField(Container container, Object itemId, Object propertyId, Component uiContext) {
            result = super.createField(container, itemId, propertyId, uiContext);
            if (result instanceof DateField) {
                ((DateField) result).setResolution(Resolution.MINUTE);

And it works as intended:

But when I refresh my page, instead of text representing my date, I see editable DateField, without any date set:

It seems quite strange for me and I don’t know why it happens.

Will be grateful for help!