SLING-9320 - Allow precompiled units to access objects from the same bundle through the Use API

* the BundledUnitManagerImpl reference should be optional
diff --git a/src/main/java/org/apache/sling/scripting/sightly/impl/engine/extension/use/RenderUnitProvider.java b/src/main/java/org/apache/sling/scripting/sightly/impl/engine/extension/use/RenderUnitProvider.java
index d3398d1..9094962 100644
--- a/src/main/java/org/apache/sling/scripting/sightly/impl/engine/extension/use/RenderUnitProvider.java
+++ b/src/main/java/org/apache/sling/scripting/sightly/impl/engine/extension/use/RenderUnitProvider.java
@@ -49,6 +49,8 @@
 import org.osgi.framework.Constants;
 import org.osgi.service.component.annotations.Component;
 import org.osgi.service.component.annotations.Reference;
+import org.osgi.service.component.annotations.ReferenceCardinality;
+import org.osgi.service.component.annotations.ReferencePolicyOption;
 import org.osgi.service.metatype.annotations.AttributeDefinition;
 
 /**
@@ -76,7 +78,7 @@
     @Reference
     private ScriptCache scriptCache;
 
-    @Reference
+    @Reference(cardinality = ReferenceCardinality.OPTIONAL, policyOption=ReferencePolicyOption.GREEDY)
     private BundledUnitManagerImpl bundledUnitManager;
 
     @Reference