[FIR] Replace Deprecated with PrivateForInline in ScopeSession

compiler/fir/tree/src/org/jetbrains/kotlin/fir/PrivateForInline.kt

@@ -0,0 +1,9 @@
+/*
+ * Copyright 2010-2020 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.fir
+
+@RequiresOptIn(level = RequiresOptIn.Level.ERROR)
+annotation class PrivateForInline

compiler/fir/tree/src/org/jetbrains/kotlin/fir/resolve/ScopeSession.kt

@@ -5,16 +5,18 @@
 
 package org.jetbrains.kotlin.fir.resolve
 
+import org.jetbrains.kotlin.fir.PrivateForInline
+
 class ScopeSession {
     private val scopes = hashMapOf<Any, HashMap<ScopeSessionKey<*, *>, Any>>()
 
     var returnTypeCalculator: Any? = null
 
-    @Deprecated(level = DeprecationLevel.ERROR, message = "Only for getOrBuild")
+    @PrivateForInline
     fun scopes() = scopes
 
+    @OptIn(PrivateForInline::class)
     inline fun <reified ID : Any, reified FS : Any> getOrBuild(id: ID, key: ScopeSessionKey<ID, FS>, build: () -> FS): FS {
-        @Suppress("DEPRECATION_ERROR")
         return scopes().getOrPut(id) {
             hashMapOf()
         }.getOrPut(key) {