def _set_contents(self, force=False):
        """
        Updates the .contents attribute of the value with the encoded value of
        all of the child objects

        :param force:
            Ensure all contents are in DER format instead of possibly using
            cached BER-encoded data
        """

        if self.children is None:
            self._parse_children()

        contents = BytesIO()
        for index, info in enumerate(self._fields):
            child = self.children[index]
            if child is None:
                child_dump = b''
            elif child.__class__ == tuple:
                if force:
                    child_dump = self._lazy_child(index).dump(force=force)
                else:
                    child_dump = child[3] + child[4] + child[5]
            else:
                child_dump = child.dump(force=force)
            # Skip values that are the same as the default
            if info[2] and 'default' in info[2]:
                default_value = info[1](**info[2])
                if default_value.dump() == child_dump:
                    continue
            contents.write(child_dump)
        self._contents = contents.getvalue()

        self._header = None
        if self._trailer != b'':
            self._trailer = b''
Updates the .contents attribute of the value with the encoded value of
        all of the child objects

        :param force:
            Ensure all contents are in DER format instead of possibly using
            cached BER-encoded data