[bs-73] Tweak configuration class detection algorithm some more

This looks like becoming a recurring theme. Unfortunately it's
not very easy to test if a class might eventually be instantiatable
by Spring.

This change fixes the main bootstrap SpringApplicationTests
which were failing because they used non-static inner classes
for test configurations.

spring-bootstrap/src/main/java/org/springframework/bootstrap/BeanDefinitionLoader.java

@@ -24,12 +24,14 @@ import org.springframework.beans.factory.support.BeanNameGenerator;
 import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;
 import org.springframework.context.annotation.AnnotatedBeanDefinitionReader;
 import org.springframework.context.annotation.ClassPathBeanDefinitionScanner;
+import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.io.DefaultResourceLoader;
 import org.springframework.core.io.Resource;
 import org.springframework.core.io.ResourceLoader;
 import org.springframework.core.type.filter.AbstractTypeHierarchyTraversingFilter;
 import org.springframework.core.type.filter.TypeFilter;
+import org.springframework.stereotype.Component;
 import org.springframework.util.Assert;
 
 /**
@@ -154,6 +156,11 @@ class BeanDefinitionLoader {
 	}
 
 	private boolean isComponent(Class<?> type) {
+		// This has to be a bit of a guess. The only way to be sure that this type is
+		// eligible is to make a bean definition out of it and try to instantiate it.
+		if (AnnotationUtils.findAnnotation(type, Component.class) != null) {
+			return true;
+		}
 		// Nested anonymous classes are not eligible for registration, nor are groovy
 		// closures
 		if (type.isAnonymousClass() || type.getName().contains("$_closure")

spring-bootstrap/src/test/java/org/springframework/bootstrap/SpringApplicationTests.java

@@ -24,7 +24,6 @@ import org.springframework.beans.BeansException;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.BeanNameGenerator;
 import org.springframework.beans.factory.support.DefaultBeanNameGenerator;
-import org.springframework.bootstrap.context.annotation.EnableAutoConfiguration;
 import org.springframework.bootstrap.context.embedded.AnnotationConfigEmbeddedWebApplicationContext;
 import org.springframework.bootstrap.context.embedded.jetty.JettyEmbeddedServletContainerFactory;
 import org.springframework.context.ApplicationContext;
@@ -331,7 +330,6 @@ public class SpringApplicationTests {
 	}
 
 	@Configuration
-	@EnableAutoConfiguration
 	static class ExampleWebConfig {
 
 		@Bean