Add unit tests asserting the behavior of Java Object.toString() used in various contexts, such as Optionals and Streams.

spring-geode-autoconfigure/src/test/java/example/java/lang/ObjectToStringWithOptionalUnitTests.java

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+/*
+ * Copyright 2018 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
+ *
+ *     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 example.java.lang;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Optional;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.junit.Test;
+
+/**
+ * Unit test for {@link Object#toString()} with {@link Optional} of {@literal null}.
+ *
+ * @author John Blum
+ * @see java.lang.Object
+ * @see java.util.Optional
+ * @since 1.0.0
+ */
+public class ObjectToStringWithOptionalUnitTests {
+
+	@Test
+	@SuppressWarnings("all")
+	public void objectToStringWithOptionalOfNull() {
+
+		assertThat(Optional.ofNullable(null).map(Object::toString).orElse("test"))
+			.isEqualTo("test");
+	}
+
+	@Test(expected = NullPointerException.class)
+	public void objectToStringWithStreamOfElementsContainingNullThrowsNullPointerException() {
+
+		assertThat(Stream.of(1, null, 3).map(Object::toString).collect(Collectors.toList()))
+			.containsExactly("1", "null", "3");
+	}
+
+	@Test
+	public void stringValueOfWithStreamOfElementsContainingNullIsNullSafe() {
+
+		assertThat(Stream.of(1, null, 3).map(String::valueOf).collect(Collectors.toList()))
+			.containsExactly("1", "null", "3");
+	}
+}