petclinic owners ui - unused name field becomes the text 'undefined'

[stevelr]

If you fill in first name 'Bob' and no last name, then submit, the user entered shows as 'Bob undefined'. Similarly if you enter last name only the user shows up as 'undefined Last'. However, if you click the other field to focus, type a space, and then backspace (erase the space, so the text field is blank), instead of "Bob undefined" you get "Bob".