Use default SslContextFactory for JettyClient

Update the auto-configured Jetty `HttpClient` so that a default
`SslContextFactory` is used.

Prior to this commit connecting to https URLs would cause a
`NullPointerException`.

Fixed gh-16810

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/reactive/function/client/ClientHttpConnectorConfiguration.java

 /*
- * Copyright 2012-2018 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -18,6 +18,9 @@ package org.springframework.boot.autoconfigure.web.reactive.function.client;
 
 import java.util.function.Function;
 
+import org.eclipse.jetty.client.HttpClient;
+import org.eclipse.jetty.util.ssl.SslContextFactory;
+
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
 import org.springframework.context.annotation.Bean;
@@ -73,8 +76,12 @@ class ClientHttpConnectorConfiguration {
 		@Bean
 		public JettyClientHttpConnector jettyClientHttpConnector(
 				JettyResourceFactory jettyResourceFactory) {
-			return new JettyClientHttpConnector(jettyResourceFactory, (httpClient) -> {
-			});
+			SslContextFactory sslContextFactory = new SslContextFactory.Client();
+			HttpClient httpClient = new HttpClient(sslContextFactory);
+			httpClient.setExecutor(jettyResourceFactory.getExecutor());
+			httpClient.setByteBufferPool(jettyResourceFactory.getByteBufferPool());
+			httpClient.setScheduler(jettyResourceFactory.getScheduler());
+			return new JettyClientHttpConnector(httpClient);
 		}
 
 	}

spring-boot-project/spring-boot-autoconfigure/src/test/java/org/springframework/boot/autoconfigure/web/reactive/function/client/ClientHttpConnectorConfigurationTests.java

+/*
+ * Copyright 2012-2019 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.boot.autoconfigure.web.reactive.function.client;
+
+import java.util.concurrent.Executor;
+
+import org.eclipse.jetty.client.HttpClient;
+import org.eclipse.jetty.io.ByteBufferPool;
+import org.eclipse.jetty.util.thread.Scheduler;
+import org.junit.Test;
+
+import org.springframework.http.client.reactive.JettyClientHttpConnector;
+import org.springframework.http.client.reactive.JettyResourceFactory;
+import org.springframework.test.util.ReflectionTestUtils;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+/**
+ * Tests for {@link ClientHttpConnectorConfiguration}.
+ *
+ * @author Phillip Webb
+ */
+public class ClientHttpConnectorConfigurationTests {
+
+	@Test
+	public void jettyClientHttpConnectorAppliesJettyResourceFactory() {
+		Executor executor = mock(Executor.class);
+		ByteBufferPool byteBufferPool = mock(ByteBufferPool.class);
+		Scheduler scheduler = mock(Scheduler.class);
+		JettyResourceFactory jettyResourceFactory = new JettyResourceFactory();
+		jettyResourceFactory.setExecutor(executor);
+		jettyResourceFactory.setByteBufferPool(byteBufferPool);
+		jettyResourceFactory.setScheduler(scheduler);
+		JettyClientHttpConnector connector = new ClientHttpConnectorConfiguration.JettyClient()
+				.jettyClientHttpConnector(jettyResourceFactory);
+		HttpClient httpClient = (HttpClient) ReflectionTestUtils.getField(connector,
+				"httpClient");
+		assertThat(httpClient.getExecutor()).isSameAs(executor);
+		assertThat(httpClient.getByteBufferPool()).isSameAs(byteBufferPool);
+		assertThat(httpClient.getScheduler()).isSameAs(scheduler);
+	}
+
+	@Test
+	public void JettyResourceFactoryHasSslContextFactory() {
+		// gh-16810
+		JettyResourceFactory jettyResourceFactory = new JettyResourceFactory();
+		JettyClientHttpConnector connector = new ClientHttpConnectorConfiguration.JettyClient()
+				.jettyClientHttpConnector(jettyResourceFactory);
+		HttpClient httpClient = (HttpClient) ReflectionTestUtils.getField(connector,
+				"httpClient");
+		assertThat(httpClient.getSslContextFactory()).isNotNull();
+	}
+
+}