Allow early OnBeanCondition filtering

Update `OnBeanCondition` to be an `AutoConfigurationImportFilter` and
filter out classes early.

See gh-13328

Author: philwebb

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/condition/OnBeanCondition.java

@@ -34,6 +34,7 @@
 import org.springframework.beans.factory.ListableBeanFactory;
 import org.springframework.beans.factory.config.BeanDefinition;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
+import org.springframework.boot.autoconfigure.AutoConfigurationMetadata;
 import org.springframework.boot.autoconfigure.condition.ConditionMessage.Style;
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Condition;
@@ -58,14 +59,49 @@
  * @author Andy Wilkinson
  */
 @Order(Ordered.LOWEST_PRECEDENCE)
-class OnBeanCondition extends SpringBootCondition implements ConfigurationCondition {
+class OnBeanCondition extends FilteringSpringBootCondition
+		implements ConfigurationCondition {
 
 	/**
 	 * Bean definition attribute name for factory beans to signal their product type (if
 	 * known and it can't be deduced from the factory bean class).
 	 */
 	public static final String FACTORY_BEAN_OBJECT_TYPE = BeanTypeRegistry.FACTORY_BEAN_OBJECT_TYPE;
 
+	@Override
+	protected final ConditionOutcome[] getOutcomes(String[] autoConfigurationClasses,
+			AutoConfigurationMetadata autoConfigurationMetadata) {
+		ConditionOutcome[] outcomes = new ConditionOutcome[autoConfigurationClasses.length];
+		for (int i = 0; i < outcomes.length; i++) {
+			String autoConfigurationClass = autoConfigurationClasses[i];
+			if (autoConfigurationClass != null) {
+				Set<String> onBeanTypes = autoConfigurationMetadata
+						.getSet(autoConfigurationClass, "ConditionalOnBean");
+				outcomes[i] = getOutcome(onBeanTypes, ConditionalOnBean.class);
+				if (outcomes[i] == null) {
+					Set<String> onSingleCandidateTypes = autoConfigurationMetadata.getSet(
+							autoConfigurationClass, "ConditionalOnSingleCandidate");
+					outcomes[i] = getOutcome(onSingleCandidateTypes,
+							ConditionalOnSingleCandidate.class);
+				}
+			}
+		}
+		return outcomes;
+	}
+
+	private ConditionOutcome getOutcome(Set<String> requiredBeanTypes,
+			Class<? extends Annotation> annotation) {
+		List<String> missing = filter(requiredBeanTypes, ClassNameFilter.MISSING,
+				getBeanClassLoader());
+		if (!missing.isEmpty()) {
+			ConditionMessage message = ConditionMessage.forCondition(annotation)
+					.didNotFind("required type", "required types")
+					.items(Style.QUOTE, missing);
+			return ConditionOutcome.noMatch(message);
+		}
+		return null;
+	}
+
 	@Override
 	public ConfigurationPhase getConfigurationPhase() {
 		return ConfigurationPhase.REGISTER_BEAN;
@@ -337,7 +373,6 @@ private BeanDefinition findBeanDefinition(ConfigurableListableBeanFactory beanFa
 					.getParentBeanFactory()), beanName, considerHierarchy);
 		}
 		return null;
-
 	}
 
 	private static class BeanSearchSpec {

spring-boot-project/spring-boot-autoconfigure/src/main/resources/META-INF/spring.factories

@@ -17,6 +17,7 @@ org.springframework.boot.autoconfigure.condition.ConditionEvaluationReportAutoCo
 
 # Auto Configuration Import Filters
 org.springframework.boot.autoconfigure.AutoConfigurationImportFilter=\
+org.springframework.boot.autoconfigure.condition.OnBeanCondition,\
 org.springframework.boot.autoconfigure.condition.OnClassCondition
 
 # Auto Configure