Issue #3395953 by just_like_good_vibes: ComponentElementBuilder, pick selected...

Issue #3395953 by just_like_good_vibes: ComponentElementBuilder, pick selected prop source if defined

src/Form/ComponentElementBuilder.php

@@ -71,7 +71,7 @@ class ComponentElementBuilder {
    */
   protected function buildProp(array $build, string $prop_id, array $definition, array $configuration, array $contexts): array {
     $prop_type = $definition['ui_patterns']['type_definition'];
-    $source_id = $this->sourcesManager->getPropTypeDefault($prop_type->getPluginId(), $contexts);
+    $source_id = array_key_exists("source_id", $configuration) ? $configuration["source_id"] : $this->sourcesManager->getPropTypeDefault($prop_type->getPluginId(), $contexts);
     if (!$source_id) {
       return $build;
     }