Cake\ORM\Association\BelongsToMany::_appendNotMatching PHP Method

    protected function _appendNotMatching($query, $options)
    {
        if (empty($options['negateMatch'])) {
            return;
        }
        if (!isset($options['conditions'])) {
            $options['conditions'] = [];
        }
        $junction = $this->junction();
        $belongsTo = $junction->association($this->source()->alias());
        $conds = $belongsTo->_joinCondition(['foreignKey' => $belongsTo->foreignKey()]);
        $subquery = $this->find()->select(array_values($conds))->where($options['conditions'])->andWhere($this->junctionConditions());
        if (!empty($options['queryBuilder'])) {
            $subquery = $options['queryBuilder']($subquery);
        }
        $assoc = $junction->association($this->target()->alias());
        $conditions = $assoc->_joinCondition(['foreignKey' => $this->targetForeignKey()]);
        $subquery = $this->_appendJunctionJoin($subquery, $conditions);
        $query->andWhere(function ($exp) use($subquery, $conds) {
            $identifiers = [];
            foreach (array_keys($conds) as $field) {
                $identifiers = new IdentifierExpression($field);
            }
            $identifiers = $subquery->newExpr()->add($identifiers)->tieWith(',');
            $nullExp = clone $exp;
            return $exp->or_([$exp->notIn($identifiers, $subquery), $nullExp->and(array_map([$nullExp, 'isNull'], array_keys($conds)))]);
        });
    }