Rewrite UnderMigration and MigrationStatus in Java

to remove dependency on kotlin-stdlib.

#KT-33141

libraries/tools/kotlin-annotations-jvm/src/kotlin/annotations/jvm/Annotations.kt

@@ -1,34 +0,0 @@
-/*
- * Copyright 2010-2017 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package kotlin.annotations.jvm
-
-/**
- * Contains the list of possible migration statuses.
- */
-public enum class MigrationStatus {
-    IGNORE,
-    WARN,
-    @Deprecated("experimental feature")
-    STRICT
-}
-
-/**
- * This meta-annotation is intended for user nullability annotations with JSR-305 type qualifiers. Behaviour of meta-annotated
- * nullability annotations can be controlled via compilation flag.
- */
-@Target(AnnotationTarget.ANNOTATION_CLASS)
-public annotation class UnderMigration(val status: MigrationStatus)

libraries/tools/kotlin-annotations-jvm/src/kotlin/annotations/jvm/MigrationStatus.java

@@ -0,0 +1,17 @@
+/*
+ * 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 kotlin.annotations.jvm;
+
+/**
+ * Contains the list of possible migration statuses.
+ */
+public enum MigrationStatus {
+    IGNORE,
+    WARN,
+    /** @deprecated experimental feature */
+    @Deprecated
+    STRICT;
+}

libraries/tools/kotlin-annotations-jvm/src/kotlin/annotations/jvm/UnderMigration.java

@@ -0,0 +1,18 @@
+/*
+ * 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 kotlin.annotations.jvm;
+
+import java.lang.annotation.*;
+
+/**
+ * This meta-annotation is intended for user nullability annotations with JSR-305 type qualifiers. Behaviour of meta-annotated
+ * nullability annotations can be controlled via compilation flag.
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Target({ElementType.ANNOTATION_TYPE})
+public @interface UnderMigration {
+    MigrationStatus status();
+}