Configure X-Forwarded-* support with Reactor Netty

This commit configures the new X-Forwarded-* / Forwarded HTTP headers
support with Reactor Netty in its 0.8.0 version.

Closes gh-10900

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/embedded/NettyWebServerFactoryCustomizerTests.java

@@ -0,0 +1,75 @@
+/*
+ * Copyright 2012-2018 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 org.springframework.boot.autoconfigure.web.embedded;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.boot.autoconfigure.web.ServerProperties;
+import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
+import org.springframework.boot.web.embedded.netty.NettyReactiveWebServerFactory;
+import org.springframework.mock.env.MockEnvironment;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+/**
+ * Tests for {@link NettyWebServerFactoryCustomizer}.
+ *
+ * @author Brian Clozel
+ */
+public class NettyWebServerFactoryCustomizerTests {
+
+	private MockEnvironment environment;
+
+	private ServerProperties serverProperties;
+
+	private NettyWebServerFactoryCustomizer customizer;
+
+	@Before
+	public void setup() {
+		this.environment = new MockEnvironment();
+		this.serverProperties = new ServerProperties();
+		ConfigurationPropertySources.attach(this.environment);
+		this.customizer = new NettyWebServerFactoryCustomizer(this.environment,
+				this.serverProperties);
+	}
+
+	@Test
+	public void deduceUseForwardHeadersUndertow() {
+		this.environment.setProperty("DYNO", "-");
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verify(factory).setUseForwardHeaders(true);
+	}
+
+	@Test
+	public void defaultUseForwardHeadersUndertow() {
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verify(factory).setUseForwardHeaders(false);
+	}
+
+	@Test
+	public void setUseForwardHeadersUndertow() {
+		this.serverProperties.setUseForwardHeaders(true);
+		NettyReactiveWebServerFactory factory = mock(NettyReactiveWebServerFactory.class);
+		this.customizer.customize(factory);
+		verify(factory).setUseForwardHeaders(true);
+	}
+
+}