title: JPA: is the default constructor required to be empty?
body: <p>Is it necessary that the default contructor is empty when working with JPA?
  Since I have no clue of how JPA internally works I somehow fear that an object could be falsely initialised by JPA when the default contructor does some stuff on his own like filling attributes with default values and the like.</p>
  
  <p>Thanks.</p>