Add OptionalCheckReturnValue

Author: Zac Sweers

src/main/java/io/reactivex/annotations/OptionalCheckReturnValue.java

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) 2016-present, RxJava Contributors.
+ *
+ * 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 io.reactivex.annotations;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Marks methods whose return values should be optionally checked by separate tooling.
+ * <p>History: 2.2.4 - experimental
+ * @since 2.2.4
+ */
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@Target(ElementType.METHOD)
+public @interface OptionalCheckReturnValue {
+
+}