Inject the class loader from the parent context into the child context more aggressively.

`ConditionEvaluator` extracts the class loader from the bean factory at instantiation, and then uses said classloader to load classes when evaluating conditionals. Hence, we need to inject the parent class loader into a bean factory that we inject into the child context. This fix is an extension of the fix made in spring-cloud/spring-cloud-netflix#3101.

Fixes spring-cloud/spring-cloud-openfeign#475

Author: tommyk-gears

spring-cloud-context/src/main/java/org/springframework/cloud/context/named/NamedContextFactory.java

@@ -29,9 +29,11 @@
 import org.springframework.beans.factory.DisposableBean;
 import org.springframework.beans.factory.NoSuchBeanDefinitionException;
 import org.springframework.beans.factory.ObjectProvider;
+import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.autoconfigure.context.PropertyPlaceholderAutoConfiguration;
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.ApplicationContextAware;
+import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.core.ResolvableType;
 import org.springframework.core.env.MapPropertySource;
@@ -110,7 +112,25 @@ protected AnnotationConfigApplicationContext getContext(String name) {
 	}
 
 	protected AnnotationConfigApplicationContext createContext(String name) {
-		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
+		AnnotationConfigApplicationContext context;
+		if (this.parent != null) {
+			// jdk11 issue
+			// https://github.com/spring-cloud/spring-cloud-netflix/issues/3101
+			// https://github.com/spring-cloud/spring-cloud-openfeign/issues/475
+			DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
+			if (parent instanceof ConfigurableApplicationContext) {
+				beanFactory.setBeanClassLoader(
+						((ConfigurableApplicationContext) parent).getBeanFactory().getBeanClassLoader());
+			}
+			else {
+				beanFactory.setBeanClassLoader(parent.getClassLoader());
+			}
+			context = new AnnotationConfigApplicationContext(beanFactory);
+			context.setClassLoader(this.parent.getClassLoader());
+		}
+		else {
+			context = new AnnotationConfigApplicationContext();
+		}
 		if (this.configurations.containsKey(name)) {
 			for (Class<?> configuration : this.configurations.get(name).getConfiguration()) {
 				context.register(configuration);
@@ -129,9 +149,6 @@ protected AnnotationConfigApplicationContext createContext(String name) {
 		if (this.parent != null) {
 			// Uses Environment from parent as well as beans
 			context.setParent(this.parent);
-			// jdk11 issue
-			// https://github.com/spring-cloud/spring-cloud-netflix/issues/3101
-			context.setClassLoader(this.parent.getClassLoader());
 		}
 		context.setDisplayName(generateDisplayName(name));
 		context.refresh();

spring-cloud-context/src/test/java/org/springframework/cloud/context/named/NamedContextFactoryTests.java

@@ -18,12 +18,20 @@
 
 import java.util.Arrays;
 import java.util.Map;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
 
 import org.assertj.core.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.context.annotation.AnnotationConfigApplicationContext;
 import org.springframework.context.annotation.Bean;
+import org.springframework.context.support.GenericApplicationContext;
+import org.springframework.util.ClassUtils;
 
 import static org.assertj.core.api.BDDAssertions.then;
 
@@ -37,6 +45,10 @@ public void testChildContexts() {
 		AnnotationConfigApplicationContext parent = new AnnotationConfigApplicationContext();
 		parent.register(BaseConfig.class);
 		parent.refresh();
+		testChildContexts(parent);
+	}
+
+	private void testChildContexts(GenericApplicationContext parent) {
 		TestClientFactory factory = new TestClientFactory();
 		factory.setApplicationContext(parent);
 		factory.setConfigurations(Arrays.asList(getSpec("foo", FooConfig.class), getSpec("bar", BarConfig.class)));
@@ -79,6 +91,10 @@ public void testChildContexts() {
 		then(fooContext.getClassLoader()).as("foo context classloader does not match parent")
 				.isSameAs(parent.getClassLoader());
 
+		then(fooContext.getBeanFactory().getBeanClassLoader())
+				.as("foo context bean factory classloader does not match parent")
+				.isSameAs(parent.getBeanFactory().getBeanClassLoader());
+
 		Assertions.assertThat(fooContext).hasFieldOrPropertyWithValue("customClassLoader", true);
 
 		factory.destroy();
@@ -88,10 +104,40 @@ public void testChildContexts() {
 		then(barContext.isActive()).as("bar context wasn't closed").isFalse();
 	}
 
+	@Test
+	public void testBadThreadContextClassLoader() throws InterruptedException, ExecutionException, TimeoutException {
+
+		AnnotationConfigApplicationContext parent = new AnnotationConfigApplicationContext();
+		parent.setClassLoader(ClassUtils.getDefaultClassLoader());
+		parent.register(BaseConfig.class);
+		parent.refresh();
+
+		ExecutorService es = Executors.newSingleThreadExecutor(r -> {
+			Thread t = new Thread(r);
+			t.setContextClassLoader(new ThrowingClassLoader());
+			return t;
+		});
+
+		es.submit(() -> this.testChildContexts(parent)).get(5, TimeUnit.SECONDS);
+	}
+
 	private TestSpec getSpec(String name, Class<?> configClass) {
 		return new TestSpec(name, new Class[] { configClass });
 	}
 
+	static class ThrowingClassLoader extends ClassLoader {
+
+		ThrowingClassLoader() {
+			super("Throwing classloader", null);
+		}
+
+		@Override
+		public Class<?> loadClass(String name) throws ClassNotFoundException {
+			throw new ClassNotFoundException(name);
+		}
+
+	}
+
 	static class TestClientFactory extends NamedContextFactory<TestSpec> {
 
 		TestClientFactory() {
@@ -147,6 +193,7 @@ static class Baz {
 
 	}
 
+	@ConditionalOnClass(Object.class)
 	static class FooConfig {
 
 		@Bean