Fix annotation class modality in stubs

^KT-49428

compiler/ir/ir.tree/src/org/jetbrains/kotlin/ir/util/DeclarationStubGenerator.kt

@@ -244,6 +244,14 @@ abstract class DeclarationStubGenerator(
         }
     }
 
+    // in IR Generator enums also have special handling, but here we have not enough data for it
+    // probably, that is not a problem, because you can't add new enum value to external module
+    private fun getEffectiveModality(classDescriptor: ClassDescriptor): Modality =
+        if (DescriptorUtils.isAnnotationClass(classDescriptor))
+            Modality.OPEN
+        else
+            classDescriptor.modality
+
     fun generateClassStub(descriptor: ClassDescriptor): IrClass {
         val referenceClass = symbolTable.referenceClass(descriptor)
         if (referenceClass.isBound) {
@@ -254,7 +262,7 @@ abstract class DeclarationStubGenerator(
             IrLazyClass(
                 UNDEFINED_OFFSET, UNDEFINED_OFFSET, origin,
                 it, descriptor,
-                descriptor.name, descriptor.kind, descriptor.visibility, descriptor.modality,
+                descriptor.name, descriptor.kind, descriptor.visibility, getEffectiveModality(descriptor),
                 isCompanion = descriptor.isCompanionObject,
                 isInner = descriptor.isInner,
                 isData = descriptor.isData,