TASK: Improve docs and readability of Node::getProperty (and related)

Neos.ContentRepository.Core/Classes/Feature/NodeModification/Dto/SerializedPropertyValue.php

@@ -33,7 +33,7 @@ public function __construct(
     }
 
     /**
-     * @param array<string,mixed> $valueAndType
+     * @param array{type:string,value:mixed} $valueAndType
      */
     public static function fromArray(array $valueAndType): self
     {

Neos.ContentRepository.Core/Classes/Feature/NodeModification/Dto/SerializedPropertyValues.php

@@ -43,7 +43,7 @@ public static function createEmpty(): self
     }
 
     /**
-     * @param array<string,mixed> $propertyValues
+     * @param array<string,array{type:string,value:mixed}|SerializedPropertyValue|null> $propertyValues
      */
     public static function fromArray(array $propertyValues): self
     {
@@ -129,6 +129,9 @@ public function splitByScope(NodeType $nodeType): array
         );
     }
 
+    /**
+     * @phpstan-assert-if-true !null $this->getProperty()
+     */
     public function propertyExists(string $propertyName): bool
     {
         return isset($this->values[$propertyName]);

Neos.ContentRepository.Core/Classes/Projection/ContentGraph/Node.php

@@ -29,21 +29,23 @@
  *
  * The node does not have structure information, i.e. no infos
  * about its children. To f.e. fetch children, you need to fetch
- * the subgraph via $node->subgraphIdentity and then
- * call findChildNodes() on the subgraph.
+ * the subgraph {@see ContentGraphInterface::getSubgraph()} via
+ * $subgraphIdentity {@see Node::$subgraphIdentity}. and then
+ * call findChildNodes() {@see ContentSubgraphInterface::findChildNodes()}
+ * on the subgraph.
  *
  * @api Note: The constructor is not part of the public API
  */
 final readonly class Node
 {
     /**
-     * @param ContentSubgraphIdentity $subgraphIdentity This is part of the node's "Read Model" identity which is defined by: {@see self::subgraphIdentity} and {@see self::nodeAggregateId}
+     * @param ContentSubgraphIdentity $subgraphIdentity This is part of the node's "Read Model" identity which is defined by: {@see self::subgraphIdentity} and {@see self::nodeAggregateId}. With this information, you can fetch a Subgraph using {@see ContentGraphInterface::getSubgraph()}.
      * @param NodeAggregateId $nodeAggregateId NodeAggregateId (identifier) of this node. This is part of the node's "Read Model" identity which is defined by: {@see self::subgraphIdentity} and {@see self::nodeAggregateId}
      * @param OriginDimensionSpacePoint $originDimensionSpacePoint The DimensionSpacePoint the node originates in. Usually needed to address a Node in a NodeAggregate in order to update it.
      * @param NodeAggregateClassification $classification The classification (regular, root, tethered) of this node
      * @param NodeTypeName $nodeTypeName The node's node type name; always set, even if unknown to the NodeTypeManager
      * @param NodeType|null $nodeType The node's node type, null if unknown to the NodeTypeManager - @deprecated Don't rely on this too much, as the capabilities of the NodeType here will probably change a lot; Ask the {@see NodeTypeManager} instead
-     * @param PropertyCollection $properties All properties of this node. References are NOT part of this API; To access references, {@see ContentSubgraphInterface::findReferences()} can be used; To read the serialized properties, call properties->serialized().
+     * @param PropertyCollection $properties All properties of this node. References are NOT part of this API; To access references, {@see ContentSubgraphInterface::findReferences()} can be used; To read the serialized properties use {@see PropertyCollection::serialized()}.
      * @param NodeName|null $nodeName The optional name of this node {@see ContentSubgraphInterface::findChildNodeConnectedThroughEdgeName()}
      * @param Timestamps $timestamps Creation and modification timestamps of this node
      */
@@ -69,18 +71,15 @@ public static function create(ContentSubgraphIdentity $subgraphIdentity, NodeAgg
     }
 
     /**
-     * Returns the specified property.
-     *
-     * If the node has a content object attached, the property will be fetched
-     * there if it is gettable.
+     * Returns the specified property, or null if it does not exist (or was set to null -> unset)
      *
      * @param string $propertyName Name of the property
      * @return mixed value of the property
      * @api
      */
     public function getProperty(string $propertyName): mixed
     {
-        return $this->properties[$propertyName];
+        return $this->properties->offsetGet($propertyName);
     }
 
     /**

Neos.ContentRepository.Core/Classes/Projection/ContentGraph/PropertyCollection.php

@@ -24,7 +24,7 @@
  * @implements \IteratorAggregate<string,mixed>
  * @api This object should not be instantiated by 3rd parties, but it is part of the {@see Node} read model
  */
-final class PropertyCollection implements \ArrayAccess, \IteratorAggregate
+final class PropertyCollection implements \ArrayAccess, \IteratorAggregate, \Countable
 {
     /**
      * Properties from Nodes
@@ -56,14 +56,16 @@ public function offsetExists($offset): bool
 
     public function offsetGet($offset): mixed
     {
-        if (!isset($this->deserializedPropertyValuesRuntimeCache[$offset])) {
-            $serializedProperty = $this->serializedPropertyValues->getProperty($offset);
-            $this->deserializedPropertyValuesRuntimeCache[$offset] = $serializedProperty === null
-                ? null
-                : $this->propertyConverter->deserializePropertyValue($serializedProperty);
+        if (array_key_exists($offset, $this->deserializedPropertyValuesRuntimeCache)) {
+            return $this->deserializedPropertyValuesRuntimeCache[$offset];
         }
 
-        return $this->deserializedPropertyValuesRuntimeCache[$offset];
+        $serializedProperty = $this->serializedPropertyValues->getProperty($offset);
+        if ($serializedProperty === null) {
+            return null;
+        }
+        return $this->deserializedPropertyValuesRuntimeCache[$offset] =
+            $this->propertyConverter->deserializePropertyValue($serializedProperty);
     }
 
     public function offsetSet($offset, $value): never
@@ -90,4 +92,9 @@ public function serialized(): SerializedPropertyValues
     {
         return $this->serializedPropertyValues;
     }
+
+    public function count(): int
+    {
+        return count($this->serializedPropertyValues);
+    }
 }

Neos.ContentRepository.NodeMigration/src/Transformation/StripTagsOnPropertyTransformationFactory.php

@@ -53,10 +53,9 @@ public function execute(
                 DimensionSpacePointSet $coveredDimensionSpacePoints,
                 ContentStreamId $contentStreamForWriting
             ): ?CommandResult {
-                if ($node->hasProperty($this->propertyName)) {
-                    $properties = $node->properties;
-                    /** @var SerializedPropertyValue $serializedPropertyValue safe since Node::hasProperty */
-                    $serializedPropertyValue = $properties->serialized()->getProperty($this->propertyName);
+                $properties = $node->properties->serialized();
+                if ($properties->propertyExists($this->propertyName)) {
+                    $serializedPropertyValue = $properties->getProperty($this->propertyName);
                     $propertyValue = $serializedPropertyValue->value;
                     if (!is_string($propertyValue)) {
                         throw new \Exception(