@NotNull
  public Date getDateOfBirth() {
    GregorianCalendar calendar = new GregorianCalendar(birthYear, birthMonth, birthDay);
    return calendar.getTime();
  }
@NotNull
  public Date getDateOfBirth() {
    GregorianCalendar calendar = new GregorianCalendar(birthYear, birthMonth, birthDay);
    return calendar.getTime();
  }
@ NotNull public Date getDateOfBirth ( ) { GregorianCalendar calendar = new GregorianCalendar ( birthYear , birthMonth , birthDay ) ; return calendar . getTime ( ) ; }
Gets the date of birth for this individual.

@return the date of birth
Gets the date of birth for this individual .