Method checkin

/**
 * Method to checkin a row.
 *
 * @param   integer  $pk  The numeric id of the primary key.
 *
 * @return  boolean  False on failure or error, true otherwise.
 *
 * @since   1.6
 */
public function checkin($pk = null)
{
    // Only attempt to check the row in if it exists.
    if ($pk) {
        $user = Factory::getUser();
        // Get an instance of the row to checkin.
        $table = $this->getTable();
        if (!$table->load($pk)) {
            $this->setError($table->getError());
            return false;
        }
        // If there is no checked_out or checked_out_time field, just return true.
        if (!$table->hasField('checked_out') || !$table->hasField('checked_out_time')) {
            return true;
        }
        $checkedOutField = $table->getColumnAlias('checked_out');
        // Check if this is the user having previously checked out the row.
        if ($table->{$checkedOutField} > 0 && $table->{$checkedOutField} != $user->get('id') && !$user->authorise('core.manage', 'com_checkin')) {
            $this->setError(Text::_('JLIB_APPLICATION_ERROR_CHECKIN_USER_MISMATCH'));
            return false;
        }
        // Attempt to check the row in.
        if (!$table->checkIn($pk)) {
            $this->setError($table->getError());
            return false;
        }
    }
    return true;
}