When using this query :

em.createQuery("Select New MYPACKAGE.Object(o.date)
from Object o");

While the used constructor is the following :

public Object(java.sql.Date date)

An "Unable to locate appropriate constructor on class" error is caught.

Solved the issue locally by using a cast in the constructor while changing the entry type to java.util.Date :

public Object(java.util.Date date)