[FIR] Add cfg reference to classes

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/declarations/FirJavaClass.kt

@@ -18,6 +18,8 @@ import org.jetbrains.kotlin.fir.declarations.builder.AbstractFirRegularClassBuil
 import org.jetbrains.kotlin.fir.declarations.impl.FirDeclarationStatusImpl
 import org.jetbrains.kotlin.fir.expressions.FirAnnotationCall
 import org.jetbrains.kotlin.fir.java.JavaTypeParameterStack
+import org.jetbrains.kotlin.fir.references.FirControlFlowGraphReference
+import org.jetbrains.kotlin.fir.references.impl.FirEmptyControlFlowGraphReference
 import org.jetbrains.kotlin.fir.scopes.FirScopeProvider
 import org.jetbrains.kotlin.fir.symbols.impl.FirRegularClassSymbol
 import org.jetbrains.kotlin.fir.types.FirTypeRef
@@ -46,6 +48,7 @@ class FirJavaClass @FirImplementationDetail internal constructor(
     internal val existingNestedClassifierNames: List<Name>
 ) : FirRegularClass() {
     override val hasLazyNestedClassifiers: Boolean get() = true
+    override val controlFlowGraphReference: FirControlFlowGraphReference get() = FirEmptyControlFlowGraphReference
 
     init {
         symbol.bind(this)
@@ -85,6 +88,10 @@ class FirJavaClass @FirImplementationDetail internal constructor(
         status = status.transformSingle(transformer, data)
         return this
     }
+
+    override fun <D> transformControlFlowGraphReference(transformer: FirTransformer<D>, data: D): FirRegularClass {
+        return this
+    }
 }
 
 @FirBuilderDsl
@@ -151,6 +158,13 @@ internal class FirJavaClassBuilder : AbstractFirRegularClassBuilder, FirAnnotati
         set(value) {
             throw IllegalStateException()
         }
+
+    @Deprecated("Modification of 'controlFlowGraphReference' has no impact for FirClassImplBuilder", level = DeprecationLevel.HIDDEN)
+    override var controlFlowGraphReference: FirControlFlowGraphReference
+        get() = throw IllegalStateException()
+        set(value) {
+            throw IllegalStateException()
+        }
 }
 
 internal inline fun buildJavaClass(init: FirJavaClassBuilder.() -> Unit): FirJavaClass {