activity/object/object.php
public function setId($id)
    {
        if (!is_null($id)) {
            $id = (string) $id;
        }

        $this->id = $id;
        return $this;
    }
public function setId($id)
    {
        if (!is_null($id)) {
            $id = (string) $id;
        }

        $this->id = $id;
        return $this;
    }
public function setId ( $ id ) { if ( ! is_null ( $ id ) ) { $ id = ( string ) $ id ; } $ this -> id = $ id ; return $ this ; }
Set the Id.

@link http://activitystrea.ms/specs/json/1.0/#object See id property.

@param string|null $id The Id.
@return ComActivitiesActivityObject
Set the Id .