Case classes take in one or more parameters and then use these parameters to auto-generate equality and comparison methods such as
hashCode(). Therefore, having a case class which does not take any parameters does not make any sense. Either you meant to specify one or more parameters, or, using a case class does not fit your requirement. In such a case, it is recommended that you use a regular class instead and optionally override the
hashCode() methods yourself.
case class C()