Converter$ConversionException when editing Grid using JPAContainer

I'm trying to make my grid editable  (grid.setEditorEnabled(true);)

but when I run the application and double-click on any cell it throws the following exception 

Caused by: com.vaadin.data.util.converter.Converter$ConversionException: Unable to convert value of type java.lang.Integer to presentation type class java.lang.String. No converter is set and the types are not compatible.
    at com.vaadin.data.util.converter.ConverterUtil.convertFromModel(ConverterUtil.java:116)
    at com.vaadin.ui.AbstractField.convertFromModel(AbstractField.java:714)
    at com.vaadin.ui.AbstractField.convertFromModel(AbstractField.java:699)
    at com.vaadin.ui.AbstractField.setPropertyDataSource(AbstractField.java:635)

any idea to what could be the cause? I checked this thread here but I wasn't able to fix the issue

Ivy.xml -- <!ENTITY vaadin.version "latest.release">JPAContainer 3.2.0 (I used same structure as the container in the demo 'jpaaddressbook' here)

thanks in advance for your time

I'm also experiencing this on v7.7.13, the only difference being that I'm using BeanItemContainer instead of JPAContainer and that I've setup the proper converter for the complaining column, which is rather simple (it's a "custom" PostgreSQL type which, in the end, translates to a String which can be between a limited set of values -- more or less like an enum).

By the way, I've found (and commented in) the StackOverflow equivalent question to this thread.