Fix binding of bean with no bean definition

See gh-16180

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

@@ -102,9 +102,13 @@ public class ConfigurationPropertiesBindingPostProcessor implements BeanPostProc
 	}
 
 	private boolean hasBeenBound(String beanName) {
-		BeanDefinition beanDefinition = ((BeanDefinitionRegistry) this.applicationContext
-				.getAutowireCapableBeanFactory()).getBeanDefinition(beanName);
-		return beanDefinition instanceof ConfigurationPropertiesBeanDefinition;
+		BeanDefinitionRegistry registry = (BeanDefinitionRegistry) this.applicationContext
+				.getAutowireCapableBeanFactory();
+		if (registry.containsBeanDefinition(beanName)) {
+			BeanDefinition beanDefinition = registry.getBeanDefinition(beanName);
+			return beanDefinition instanceof ConfigurationPropertiesBeanDefinition;
+		}
+		return false;
 	}
 
 	private void bind(Object bean, String beanName, ConfigurationProperties annotation) {

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java

@@ -846,6 +846,17 @@ public class ConfigurationPropertiesTests {
 				});
 	}
 
+	@Test
+	public void loadWhenBindingOnBeanWithoutBeanDefinitionShouldBind() {
+		load(BasicConfiguration.class, "name=test");
+		BasicProperties bean = this.context.getBean(BasicProperties.class);
+		assertThat(bean.name).isEqualTo("test");
+		bean.name = "override";
+		this.context.getBean(ConfigurationPropertiesBindingPostProcessor.class)
+				.postProcessBeforeInitialization(bean, "does-not-exist");
+		assertThat(bean.name).isEqualTo("test");
+	}
+
 	private AnnotationConfigApplicationContext load(Class<?> configuration,
 			String... inlinedProperties) {
 		return load(new Class<?>[] { configuration }, inlinedProperties);