Issue #3253784 by mkalkbrenner: PHP 8.1: IteratorAggregate::getIterator(): Traversable

src/Plugin/DataType/SolrDocument.php

@@ -166,7 +166,7 @@ class SolrDocument extends TypedData implements \IteratorAggregate, ComplexDataI
   /**
    * {@inheritdoc}
    */
-  public function getIterator() {
+  public function getIterator(): \Traversable {
     return isset($this->item) ? $this->item->getIterator() : new \ArrayIterator([]);
   }
 

src/Plugin/DataType/SolrField.php

@@ -61,7 +61,7 @@ class SolrField extends TypedData implements \IteratorAggregate {
   /**
    * {@inheritdoc}
    */
-  public function getIterator() {
+  public function getIterator(): \Traversable {
     return new \ArrayIterator((array) $this->value);
   }