Add abstract utility class for working with java.util.function.Functions.

spring-geode/src/main/java/org/springframework/geode/core/util/function/FunctionUtils.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2019 the original author or authors.
+ *
+ * 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
+ *
+ *     https://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.springframework.geode.core.util.function;
+
+import java.util.function.Consumer;
+import java.util.function.Function;
+
+/**
+ * Utility methods for using Java {@link Function Functions}.
+ *
+ * @author John Blum
+ * @see Function
+ * @since 1.1.0
+ */
+@SuppressWarnings("unused")
+public abstract class FunctionUtils {
+
+  public static <T, R> Function<T, R> toNullReturningFunction(Consumer<T> consumer) {
+
+    return object -> {
+      consumer.accept(object);
+      return null;
+    };
+  }
+}