Restore compatibility with Jetty 8 when SSL is being used

ServerConnector is in different packages in Jetty 8 and Jetty 9 which
was leading to a NoClassDefFounderError when SSL was used with
Jetty 8.

This commit updates SslServerConnectorFactory to return an
AbstractConnector, a super class of ServerConnector, that is in the
same package in both Jetty 8 and Jetty 9. This class does not provide
a setPort method so the setting of the port has been pushed down into
the SslServerConnectorFactory implementation.

SSL samples for both Jetty 8 and Jetty 9 have been added to verify
SSL with both supported versions of Jetty.

Closes gh-1925

spring-boot-samples/spring-boot-sample-jetty-ssl/src/test/java/sample/jetty/SampleJettySslApplicationTests.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2012-2014 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 sample.jetty;
+
+import org.apache.http.client.HttpClient;
+import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
+import org.apache.http.conn.ssl.SSLContextBuilder;
+import org.apache.http.conn.ssl.TrustSelfSignedStrategy;
+import org.apache.http.impl.client.HttpClients;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.boot.test.IntegrationTest;
+import org.springframework.boot.test.SpringApplicationConfiguration;
+import org.springframework.boot.test.TestRestTemplate;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
+import org.springframework.test.annotation.DirtiesContext;
+import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.test.context.web.WebAppConfiguration;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * Basic integration tests for demo application.
+ *
+ * @author Dave Syer
+ */
+@RunWith(SpringJUnit4ClassRunner.class)
+@SpringApplicationConfiguration(classes = SampleJettySslApplication.class)
+@WebAppConfiguration
+@IntegrationTest("server.port:0")
+@DirtiesContext
+public class SampleJettySslApplicationTests {
+
+	@Value("${local.server.port}")
+	private int port;
+
+	@Test
+	public void testHome() throws Exception {
+		SSLConnectionSocketFactory socketFactory = new SSLConnectionSocketFactory(
+				new SSLContextBuilder().loadTrustMaterial(null,
+						new TrustSelfSignedStrategy()).build());
+
+		HttpClient httpClient = HttpClients.custom().setSSLSocketFactory(socketFactory)
+				.build();
+
+		TestRestTemplate testRestTemplate = new TestRestTemplate();
+		((HttpComponentsClientHttpRequestFactory) testRestTemplate.getRequestFactory())
+				.setHttpClient(httpClient);
+		ResponseEntity<String> entity = testRestTemplate.getForEntity(
+				"https://localhost:" + this.port, String.class);
+		assertEquals(HttpStatus.OK, entity.getStatusCode());
+		assertEquals("Hello World", entity.getBody());
+	}
+
+}