Add beanFactory context constructors

Align `WebServer` application contexts with Spring Framework by allowing
a custom beanFactory to be used on construction.

Fixes gh-8547

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/AnnotationConfigReactiveWebServerApplicationContext.java

@@ -18,6 +18,7 @@ package org.springframework.boot.web.reactive.context;
 
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.BeanNameGenerator;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigUtils;
@@ -69,6 +70,19 @@ public class AnnotationConfigReactiveWebServerApplicationContext
 		this.scanner = new ClassPathBeanDefinitionScanner(this);
 	}
 
+	/**
+	 * Create a new {@link AnnotationConfigReactiveWebServerApplicationContext} with the
+	 * given {@code DefaultListableBeanFactory}. The context needs to be populated through
+	 * {@link #register} calls and then manually {@linkplain #refresh refreshed}.
+	 * @param beanFactory the DefaultListableBeanFactory instance to use for this context
+	 */
+	public AnnotationConfigReactiveWebServerApplicationContext(
+			DefaultListableBeanFactory beanFactory) {
+		super(beanFactory);
+		this.reader = new AnnotatedBeanDefinitionReader(this);
+		this.scanner = new ClassPathBeanDefinitionScanner(this);
+	}
+
 	/**
 	 * Create a new {@link AnnotationConfigReactiveWebServerApplicationContext}, deriving
 	 * bean definitions from the given annotated classes and automatically refreshing the

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/reactive/context/ReactiveWebServerApplicationContext.java

@@ -17,6 +17,7 @@
 package org.springframework.boot.web.reactive.context;
 
 import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.web.reactive.server.ReactiveWebServerFactory;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.context.ApplicationContextException;
@@ -35,9 +36,21 @@ public class ReactiveWebServerApplicationContext
 
 	private volatile WebServer webServer;
 
+	/**
+	 * Create a new {@link ReactiveWebServerApplicationContext}.
+	 */
 	public ReactiveWebServerApplicationContext() {
 	}
 
+	/**
+	 * Create a new {@link ReactiveWebServerApplicationContext} with the given
+	 * {@code DefaultListableBeanFactory}.
+	 * @param beanFactory the DefaultListableBeanFactory instance to use for this context
+	 */
+	public ReactiveWebServerApplicationContext(DefaultListableBeanFactory beanFactory) {
+		super(beanFactory);
+	}
+
 	@Override
 	public final void refresh() throws BeansException, IllegalStateException {
 		try {

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/AnnotationConfigServletWebServerApplicationContext.java

@@ -18,6 +18,7 @@ package org.springframework.boot.web.servlet.context;
 
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.BeanNameGenerator;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
 import org.springframework.context.annotation.AnnotationConfigUtils;
 import org.springframework.context.annotation.AnnotationScopeMetadataResolver;
@@ -67,6 +68,19 @@ public class AnnotationConfigServletWebServerApplicationContext
 		this.scanner = new ClassPathBeanDefinitionScanner(this);
 	}
 
+	/**
+	 * Create a new {@link AnnotationConfigServletWebServerApplicationContext} with the
+	 * given {@code DefaultListableBeanFactory}. The context needs to be populated through
+	 * {@link #register} calls and then manually {@linkplain #refresh refreshed}.
+	 * @param beanFactory the DefaultListableBeanFactory instance to use for this context
+	 */
+	public AnnotationConfigServletWebServerApplicationContext(
+			DefaultListableBeanFactory beanFactory) {
+		super(beanFactory);
+		this.reader = new AnnotatedBeanDefinitionReader(this);
+		this.scanner = new ClassPathBeanDefinitionScanner(this);
+	}
+
 	/**
 	 * Create a new {@link AnnotationConfigServletWebServerApplicationContext}, deriving
 	 * bean definitions from the given annotated classes and automatically refreshing the

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/web/servlet/context/ServletWebServerApplicationContext.java

@@ -36,6 +36,7 @@ import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.config.Scope;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.web.server.WebServer;
 import org.springframework.boot.web.servlet.FilterRegistrationBean;
 import org.springframework.boot.web.servlet.ServletContextInitializer;
@@ -105,6 +106,21 @@ public class ServletWebServerApplicationContext extends GenericWebApplicationCon
 
 	private String namespace;
 
+	/**
+	 * Create a new {@link ServletWebServerApplicationContext}.
+	 */
+	public ServletWebServerApplicationContext() {
+	}
+
+	/**
+	 * Create a new {@link ServletWebServerApplicationContext} with the given
+	 * {@code DefaultListableBeanFactory}.
+	 * @param beanFactory the DefaultListableBeanFactory instance to use for this context
+	 */
+	public ServletWebServerApplicationContext(DefaultListableBeanFactory beanFactory) {
+		super(beanFactory);
+	}
+
 	/**
 	 * Register ServletContextAwareProcessor.
 	 * @see ServletContextAwareProcessor