Ignore CannotLoadBeanClassException in config props validator

If the bean definition type contains a placeholder value, beanFactory.getType
can throw a CannotLoadBeanClassException. We can ignore this exception while
validating the bean definitions for constructor binding beans.

Fixes gh-19207

spring-boot-project/spring-boot/src/main/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanDefinitionValidator.java

@@ -18,6 +18,7 @@
 
 import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.BeanCreationException;
+import org.springframework.beans.factory.CannotLoadBeanClassException;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.BeanFactoryPostProcessor;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
@@ -57,12 +58,18 @@ public int getOrder() {
 	}
 
 	private void validate(ConfigurableListableBeanFactory beanFactory, String beanName) {
-		Class<?> beanClass = beanFactory.getType(beanName, false);
-		if (beanClass != null && BindMethod.forType(beanClass) == BindMethod.VALUE_OBJECT) {
-			throw new BeanCreationException(beanName,
-					"@EnableConfigurationProperties or @ConfigurationPropertiesScan must be used to add "
-							+ "@ConstructorBinding type " + beanClass.getName());
+		try {
+			Class<?> beanClass = beanFactory.getType(beanName, false);
+			if (beanClass != null && BindMethod.forType(beanClass) == BindMethod.VALUE_OBJECT) {
+				throw new BeanCreationException(beanName,
+						"@EnableConfigurationProperties or @ConfigurationPropertiesScan must be used to add "
+								+ "@ConstructorBinding type " + beanClass.getName());
+			}
+		}
+		catch (CannotLoadBeanClassException ex) {
+			// Ignore
 		}
+
 	}
 
 	/**

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-xml/src/main/java/smoketest/xml/SampleSpringXmlApplication.java

@@ -23,7 +23,9 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
 
+@SpringBootApplication
 public class SampleSpringXmlApplication implements CommandLineRunner {
 
 	private static final String CONTEXT_XML = "classpath:/META-INF/application-context.xml";

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-xml/src/main/java/smoketest/xml/service/OtherService.java

@@ -0,0 +1,25 @@
+/*
+ * 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 smoketest.xml.service;
+
+public class OtherService {
+
+	public String getMessage() {
+		return "Hello Other World";
+	}
+
+}

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-xml/src/test/java/smoketest/xml/SampleSpringXmlPlaceholderBeanDefinitionTests.java

@@ -0,0 +1,59 @@
+/*
+ * 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 smoketest.xml;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import smoketest.xml.service.OtherService;
+
+import org.springframework.boot.CommandLineRunner;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.annotation.ImportResource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for XML config with placeholders in bean definitions.
+ *
+ * @author Madhura Bhave
+ */
+@SpringBootTest(
+		classes = { SampleSpringXmlApplication.class, SampleSpringXmlPlaceholderBeanDefinitionTests.TestConfig.class })
+@ExtendWith(OutputCaptureExtension.class)
+class SampleSpringXmlPlaceholderBeanDefinitionTests {
+
+	@Test
+	void beanWithPlaceholderShouldNotFail(CapturedOutput output) throws Exception {
+		assertThat(output).contains("Hello Other World");
+	}
+
+	@Configuration(proxyBeanMethods = false)
+	@ImportResource({ "classpath:/META-INF/context.xml" })
+	static class TestConfig {
+
+		@Bean
+		CommandLineRunner testCommandLineRunner(OtherService service) {
+			return (args) -> System.out.println(service.getMessage());
+		}
+
+	}
+
+}

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-xml/src/test/resources/META-INF/context.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xmlns:context="http://www.springframework.org/schema/context"
+	xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd
+				http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd">
+
+	<context:annotation-config/>
+	<context:property-placeholder/>
+
+	<bean id="otherService" class="${bean.name}"/>
+
+</beans>

spring-boot-tests/spring-boot-smoke-tests/spring-boot-smoke-test-xml/src/test/resources/application.properties

@@ -0,0 +1 @@
+bean.name=smoketest.xml.service.OtherService