Is it necessary that composite-id should be mapped to class ??

can it be like this ?

<composite-id>
  <key-property=..../>
  <key-property=..../>
</composite-id>

or should be 

<composite-id class=....>
  <key-property=..../>
  <key-property=..../>
</composite-id>

should that necessary that if we have composite key then that class should implement equals() and override() method ?

java hibernate composite-key
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