Getting components from auto generated form by property IDs

Hi there,
took over a webapp written, obviously, in Vaadin.
Some forms (I know, they are deprecated), use
com.vaadin.addon.jpacontainer.fieldfactory.FieldFactory
and are generated automatically, by
final Form form = new Form( );
form.setFormFieldFactory( fieldFactory );
form.setItemDataSource( entityItem );

I have to change some components, such as some boolean(=Checkbox) to readonly.

How do I access the components in the form?
I have the properties and I need to, e.g. propertyId=“ignore” set the corresponding checkbox to readonly.

Many thanks in advance for your help.

I could write a specialized class and construct the form according my needs, but I do not want to change too much here.

Ciao, Tom