JSON API custom controller constuctor

hello, i have to place some common code for each API method in my controller constructor.. the problem that now JSON_API_XXX_Controller get’s listed as API method! how can i hide it and still use my constructor? thanks in advance!

class JSON_API_XXX_Controller {

public JSON_API_XXX_Controller(){
 //some code goes here for both foo and bar
}

public function foo(){}

public function bar(){}

}

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