revert
diff --git a/src/main/starlark/rkt_1_4/kotlin/opts.bzl b/src/main/starlark/rkt_1_4/kotlin/opts.bzl
index 3380013..0825653 100644
--- a/src/main/starlark/rkt_1_4/kotlin/opts.bzl
+++ b/src/main/starlark/rkt_1_4/kotlin/opts.bzl
@@ -1,7 +1,3 @@
-def _map_optin_class_to_flag(values):
-    return ["-Xopt-in=%s" %v for v in values]
-
-
 _KOPTS = {
     "warn": struct(
         args = dict(
@@ -112,15 +108,6 @@
             True: ["-Xmulti-platform"],
         },
     ),
-    "x_optin": struct(
-        args = dict(
-            default = False,
-            doc = "",
-        ),
-        type = attr.string_list,
-        value_to_flag =None,
-        map_value_to_flag = _map_optin_class_to_flag
-    ),
     "x_use_ir": struct(
         args = dict(
             default = False,
@@ -194,7 +181,7 @@
     flags = []
     for n, o in _KOPTS.items():
         value = getattr(kotlinc_options, n, None)
-        flag = o.value_to_flag.get(value, None) if o.value_to_flag else o.map_value_to_flag(value)
+        flag = o.value_to_flag.get(value, None)
         if flag:
             flags.extend(flag)
     return flags