[Commonizer] Make CirProperty.[backing|delegate]FieldAnnotations non-nullable

There is effectively no difference between missing field and a field with no annotations.

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/CirProperty.kt

@@ -13,7 +13,7 @@ interface CirProperty : CirFunctionOrProperty, CirLiftedUpDeclaration {
     val isDelegate: Boolean
     val getter: CirPropertyGetter?
     val setter: CirPropertySetter?
-    val backingFieldAnnotations: List<CirAnnotation>? // null assumes no backing field
-    val delegateFieldAnnotations: List<CirAnnotation>? // null assumes no backing field
+    val backingFieldAnnotations: List<CirAnnotation>
+    val delegateFieldAnnotations: List<CirAnnotation>
     val compileTimeInitializer: CirConstantValue<*>?
 }

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/factory/CirPropertyFactory.kt

@@ -39,8 +39,8 @@ object CirPropertyFactory {
             isDelegate = source.isDelegated,
             getter = source.getter?.let(CirPropertyGetterFactory::create),
             setter = source.setter?.let(CirPropertySetterFactory::create),
-            backingFieldAnnotations = source.backingField?.annotations?.compactMap(CirAnnotationFactory::create),
-            delegateFieldAnnotations = source.delegateField?.annotations?.compactMap(CirAnnotationFactory::create),
+            backingFieldAnnotations = source.backingField?.annotations?.compactMap(CirAnnotationFactory::create).orEmpty(),
+            delegateFieldAnnotations = source.delegateField?.annotations?.compactMap(CirAnnotationFactory::create).orEmpty(),
             compileTimeInitializer = compileTimeInitializer
         )
     }
@@ -63,8 +63,8 @@ object CirPropertyFactory {
         isDelegate: Boolean,
         getter: CirPropertyGetter?,
         setter: CirPropertySetter?,
-        backingFieldAnnotations: List<CirAnnotation>?,
-        delegateFieldAnnotations: List<CirAnnotation>?,
+        backingFieldAnnotations: List<CirAnnotation>,
+        delegateFieldAnnotations: List<CirAnnotation>,
         compileTimeInitializer: CirConstantValue<*>?
     ): CirProperty {
         return CirPropertyImpl(

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/cir/impl/CirPropertyImpl.kt

@@ -27,8 +27,8 @@ data class CirPropertyImpl(
     override val isDelegate: Boolean,
     override val getter: CirPropertyGetter?,
     override val setter: CirPropertySetter?,
-    override val backingFieldAnnotations: List<CirAnnotation>?,
-    override val delegateFieldAnnotations: List<CirAnnotation>?,
+    override val backingFieldAnnotations: List<CirAnnotation>,
+    override val delegateFieldAnnotations: List<CirAnnotation>,
     override val compileTimeInitializer: CirConstantValue<*>?
 ) : CirProperty {
     // const property in "common" fragment is already lifted up

native/commonizer/src/org/jetbrains/kotlin/descriptors/commonizer/core/PropertyCommonizer.kt

@@ -45,8 +45,8 @@ class PropertyCommonizer(classifiers: CirKnownClassifiers) : AbstractFunctionOrP
             isDelegate = false,
             getter = CirPropertyGetterFactory.DEFAULT_NO_ANNOTATIONS,
             setter = setter,
-            backingFieldAnnotations = null,
-            delegateFieldAnnotations = null,
+            backingFieldAnnotations = emptyList(),
+            delegateFieldAnnotations = emptyList(),
             compileTimeInitializer = constCompileTimeInitializer
         )
     }