[flink] 02/05: [hotfix][core] Added OptionalUtils

[tw...@apache.org]

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twalthr pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/flink.git

commit 02a4d8be8011b2535920a142364ee1cbb3ecbf14
Author: Ingo Bürk <in...@tngtech.com>
AuthorDate: Thu Sep 30 10:47:25 2021 +0200

    [hotfix][core] Added OptionalUtils
---
 .../java/org/apache/flink/util/OptionalUtils.java  | 53 ++++++++++++++++++++++
 1 file changed, 53 insertions(+)

diff --git a/flink-core/src/main/java/org/apache/flink/util/OptionalUtils.java b/flink-core/src/main/java/org/apache/flink/util/OptionalUtils.java
new file mode 100644
index 0000000..2986253
--- /dev/null
+++ b/flink-core/src/main/java/org/apache/flink/util/OptionalUtils.java
@@ -0,0 +1,53 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.flink.util;
+
+import org.apache.flink.annotation.Internal;
+
+import java.util.Optional;
+import java.util.stream.Stream;
+
+/** Utilities for working with {@link Optional}. */
+@Internal
+public class OptionalUtils {
+
+    /**
+     * Converts the given {@link Optional} into a {@link Stream}.
+     *
+     * <p>This is akin to {@code Optional#stream} available in JDK9+.
+     */
+    @SuppressWarnings("OptionalUsedAsFieldOrParameterType")
+    public static <T> Stream<T> stream(Optional<T> opt) {
+        return opt.map(Stream::of).orElseGet(Stream::empty);
+    }
+
+    /** Returns the first {@link Optional} which is present. */
+    @SafeVarargs
+    public static <T> Optional<T> firstPresent(Optional<T>... opts) {
+        for (Optional<T> opt : opts) {
+            if (opt.isPresent()) {
+                return opt;
+            }
+        }
+
+        return Optional.empty();
+    }
+
+    private OptionalUtils() {}
+}