[FIR] Support java sealed class interop

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/JavaSymbolProvider.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.fir.java
 import com.intellij.openapi.progress.ProcessCanceledException
 import com.intellij.openapi.project.Project
 import com.intellij.psi.search.GlobalSearchScope
+import org.jetbrains.kotlin.builtins.jvm.JavaToKotlinClassMap
 import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.descriptors.Modality
 import org.jetbrains.kotlin.descriptors.Visibilities
@@ -316,6 +317,13 @@ class JavaSymbolProvider(
                     valueParametersForAnnotationConstructor = valueParametersForAnnotationConstructor
                 )
         }
+    }.apply {
+        if (modality == Modality.SEALED) {
+            sealedInheritors = javaClass.permittedTypes.mapNotNull { classifierType ->
+                val classifier = classifierType.classifier as? JavaClass
+                classifier?.let { JavaToKotlinClassMap.mapJavaToKotlin(it.fqName!!) }
+            }
+        }
     }
 
     private fun convertJavaFieldToFir(

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/JavaUtils.kt

@@ -63,6 +63,14 @@ internal val JavaModifierListOwner.modality: Modality
         else -> Modality.OPEN
     }
 
+internal val JavaClass.modality: Modality
+    get() = when {
+        isSealed -> Modality.SEALED
+        isAbstract -> Modality.ABSTRACT
+        isFinal -> Modality.FINAL
+        else -> Modality.OPEN
+    }
+
 internal val JavaClass.classKind: ClassKind
     get() = when {
         isAnnotationType -> ClassKind.ANNOTATION_CLASS