Fix resolving default beans. Add documentation.

Author: OlgaMaciaszek

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/interfaceclients/AbstractInterfaceClientsImportRegistrar.java

@@ -47,13 +47,20 @@
 import org.springframework.util.ObjectUtils;
 
 /**
+ * Registers bean definitions for {@code HttpClient}
+ * and {@code RSocketClient}-annotated Interface Clients
+ * in order to automatically instantiate client beans based on those interfaces.
+ *
  * @author Josh Long
  * @author Olga Maciaszek-Sharma
+ * @since 3.4.1
  */
 // TODO: Handle AOT
 public abstract class AbstractInterfaceClientsImportRegistrar
 		implements ImportBeanDefinitionRegistrar, EnvironmentAware, ResourceLoaderAware {
 
+	public static final String DEFAULT_INTERFACE_CLIENTS_ID = "interface-clients";
+
 	private static final String INTERFACE_CLIENT_SUFFIX = "InterfaceClient";
 
 	private static final String BEAN_NAME_ATTRIBUTE_NAME = "beanName";

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/interfaceclients/QualifiedBeanProvider.java

@@ -27,9 +27,15 @@
 import org.springframework.beans.factory.annotation.Qualifier;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 
+import static org.springframework.boot.autoconfigure.interfaceclients.AbstractInterfaceClientsImportRegistrar.DEFAULT_INTERFACE_CLIENTS_ID;
+
 /**
+ * Utility class containing methods that allow searching for beans
+ * with a specific qualifier, falling back to a default qualifier.
+ *
  * @author Josh Long
  * @author Olga Maciaszek-Sharma
+ * @since 3.4.1
  */
 public final class QualifiedBeanProvider {
 
@@ -44,7 +50,7 @@ public static <T> T qualifiedBean(ConfigurableListableBeanFactory beanFactory, C
 			if (logger.isDebugEnabled()) {
 				logger.debug("No qualified bean of type " + type + " found for " + clientId);
 			}
-			Map<String, T> matchingDefaultBeans = getQualifiedBeansOfType(beanFactory, type, clientId);
+			Map<String, T> matchingDefaultBeans = getQualifiedBeansOfType(beanFactory, type, DEFAULT_INTERFACE_CLIENTS_ID);
 			if (matchingDefaultBeans.size() > 1) {
 				throw new NoUniqueBeanDefinitionException(type, matchingDefaultBeans.keySet());
 			}