Fix warnings related to OptIn/UseExperimental

libraries/reflect/api/build.gradle

@@ -47,6 +47,7 @@ compileKotlin {
                             "-Xnormalize-constructor-calls=enable",
                             "-Xno-optimized-callable-references",
                             "-Xno-kotlin-nothing-value-exception",
+                            "-Xopt-in=kotlin.RequiresOptIn",
                             "-module-name", "kotlin-reflection"]
     }
 }

libraries/stdlib/jvm/src/kotlin/collections/builders/MapBuilder.kt

@@ -436,10 +436,10 @@ internal class MapBuilder<K, V> private constructor(
         private const val INITIAL_MAX_PROBE_DISTANCE = 2
         private const val TOMBSTONE = -1
 
-        @UseExperimental(ExperimentalStdlibApi::class)
+        @OptIn(ExperimentalStdlibApi::class)
         private fun computeHashSize(capacity: Int): Int = (capacity.coerceAtLeast(1) * 3).takeHighestOneBit()
 
-        @UseExperimental(ExperimentalStdlibApi::class)
+        @OptIn(ExperimentalStdlibApi::class)
         private fun computeShift(hashSize: Int): Int = hashSize.countLeadingZeroBits() + 1
     }