Configure a JerseyApplicationPath bean for the actuators

This commit also ensures that Jersey-based actuator endpoints are
available before the user has configured a `ResourceConfig` bean

Fixes gh-15625
Fixes gh-15877

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/jersey/JerseyAutoConfiguration.java

@@ -24,7 +24,6 @@ import javax.servlet.DispatcherType;
 import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration;
-import javax.ws.rs.ApplicationPath;
 import javax.ws.rs.ext.ContextResolver;
 
 import com.fasterxml.jackson.databind.AnnotationIntrospector;
@@ -51,6 +50,7 @@ import org.springframework.boot.autoconfigure.condition.ConditionalOnSingleCandi
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication.Type;
 import org.springframework.boot.autoconfigure.jackson.JacksonAutoConfiguration;
+import org.springframework.boot.autoconfigure.web.servlet.DefaultJerseyApplicationPath;
 import org.springframework.boot.autoconfigure.web.servlet.DispatcherServletAutoConfiguration;
 import org.springframework.boot.autoconfigure.web.servlet.JerseyApplicationPath;
 import org.springframework.boot.context.properties.EnableConfigurationProperties;
@@ -60,10 +60,8 @@ import org.springframework.boot.web.servlet.ServletRegistrationBean;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.Ordered;
-import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.annotation.Order;
 import org.springframework.util.ClassUtils;
-import org.springframework.util.StringUtils;
 import org.springframework.web.WebApplicationInitializer;
 import org.springframework.web.context.ServletContextAware;
 
@@ -114,15 +112,8 @@ public class JerseyAutoConfiguration implements ServletContextAware {
 	@Bean
 	@ConditionalOnMissingBean
 	public JerseyApplicationPath jerseyApplicationPath() {
-		return this::resolveApplicationPath;
-	}
-
-	private String resolveApplicationPath() {
-		if (StringUtils.hasLength(this.jersey.getApplicationPath())) {
-			return this.jersey.getApplicationPath();
-		}
-		return findApplicationPath(AnnotationUtils.findAnnotation(
-				this.config.getApplication().getClass(), ApplicationPath.class));
+		return new DefaultJerseyApplicationPath(this.jersey.getApplicationPath(),
+				this.config);
 	}
 
 	@Bean
@@ -171,14 +162,6 @@ public class JerseyAutoConfiguration implements ServletContextAware {
 		this.jersey.getInit().forEach(registration::addInitParameter);
 	}
 
-	private static String findApplicationPath(ApplicationPath annotation) {
-		// Jersey doesn't like to be the default servlet, so map to /* as a fallback
-		if (annotation == null) {
-			return "/*";
-		}
-		return annotation.value();
-	}
-
 	@Override
 	public void setServletContext(ServletContext servletContext) {
 		String servletRegistrationName = getServletRegistrationName();

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/web/servlet/DefaultJerseyApplicationPath.java

@@ -0,0 +1,64 @@
+/*
+ * 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.servlet;
+
+import javax.ws.rs.ApplicationPath;
+
+import org.glassfish.jersey.server.ResourceConfig;
+
+import org.springframework.boot.autoconfigure.jersey.JerseyProperties;
+import org.springframework.core.annotation.AnnotationUtils;
+import org.springframework.util.StringUtils;
+
+/**
+ * Default implementation of {@link JerseyApplicationPath} that derives the path from
+ * {@link JerseyProperties} or the {@code @ApplicationPath} annotation.
+ *
+ * @author Madhura Bhave
+ */
+public class DefaultJerseyApplicationPath implements JerseyApplicationPath {
+
+	private final String applicationPath;
+
+	private final ResourceConfig config;
+
+	public DefaultJerseyApplicationPath(String applicationPath, ResourceConfig config) {
+		this.applicationPath = applicationPath;
+		this.config = config;
+	}
+
+	@Override
+	public String getPath() {
+		return resolveApplicationPath();
+	}
+
+	private String resolveApplicationPath() {
+		if (StringUtils.hasLength(this.applicationPath)) {
+			return this.applicationPath;
+		}
+		return findApplicationPath(AnnotationUtils.findAnnotation(
+				this.config.getApplication().getClass(), ApplicationPath.class));
+	}
+
+	private static String findApplicationPath(ApplicationPath annotation) {
+		// Jersey doesn't like to be the default servlet, so map to /* as a fallback
+		if (annotation == null) {
+			return "/*";
+		}
+		return annotation.value();
+	}
+
+}