matchChild example

        // caused by the (invalid) reverse transformed value should be         // ignored.
        if (null !== $relativePath) {
            // Set the scope to the root of the relative path             // This root will usually be $form. If the path contains             // an unmapped form though, the last unmapped form found             // will be the root of the path.             $scope = $relativePath->getRoot();
            $it = new PropertyPathIterator($relativePath);

            while ($this->acceptsErrors($scope) && null !== ($child = $this->matchChild($scope, $it))) {
                $scope = $child;
                $it->next();
                $match = true;
            }
        }

        // This case happens if an error happened in the data under a         // form inheriting its parent data that does not match any of the         // children of that form.         if (null !== $violationPath && !$match) {
            // If we could not map the error to anything more specific