setAddChildrenIfNoneSet example

            if ($this->default) {
                if (!\is_array($this->defaultValue)) {
                    throw new \InvalidArgumentException(sprintf('%s: the default value of an array node has to be an array.', $node->getPath()));
                }

                $node->setDefaultValue($this->defaultValue);
            }

            if (false !== $this->addDefaultChildren) {
                $node->setAddChildrenIfNoneSet($this->addDefaultChildren);
                if ($this->prototype instanceof static && !isset($this->prototype->prototype)) {
                    $this->prototype->addDefaultsIfNotSet();
                }
            }

            $this->prototype->parent = $node;
            $node->setPrototype($this->prototype->getNode());
        }

        $node->setAllowNewKeys($this->allowNewKeys);
        $node->addEquivalentValue(null, $this->nullEquivalent);
        

$children[] = ['id' => 'item_name', 'foo' => 'bar'];
        $normalized = $node->normalize($children);

        $expected = [];
        $expected['item_name'] = ['id' => 'item_name', 'foo' => 'bar'];
        $this->assertEquals($expected, $normalized);
    }

    public function testAddDefaultChildren()
    {
        $node = $this->getPrototypeNodeWithDefaultChildren();
        $node->setAddChildrenIfNoneSet();
        $this->assertTrue($node->hasDefaultValue());
        $this->assertEquals([['foo' => 'bar']], $node->getDefaultValue());

        $node = $this->getPrototypeNodeWithDefaultChildren();
        $node->setKeyAttribute('foobar');
        $node->setAddChildrenIfNoneSet();
        $this->assertTrue($node->hasDefaultValue());
        $this->assertEquals(['defaults' => ['foo' => 'bar']], $node->getDefaultValue());

        $node = $this->getPrototypeNodeWithDefaultChildren();
        $node->setKeyAttribute('foobar');