Programmatic ObjectProvider retrieval through BeanFactory API

Introduces getBeanProvider(Class) and getBeanProvider(ResolvableType), also narrowing getBean(String, Class) and isTypeMatch(String, Class) to a non-null Class argument and enriching NoUniqueBeanDefinitionException with a full ResolvableType. In addition, ObjectProvider supports iterable/stream access for collection-style resolution of multiple matching beans now, and collection injection falls back to an empty collection in a single-constructor case with non-null arguments.

Issue: SPR-17075
Issue: SPR-11419
Issue: SPR-15338

spring-context/src/test/java/org/springframework/context/annotation/AnnotationConfigApplicationContextTests.java

@@ -44,12 +44,6 @@ import static org.springframework.util.StringUtils.*;
  */
 public class AnnotationConfigApplicationContextTests {
 
-	@Test(expected = IllegalArgumentException.class)
-	public void nullGetBeanParameterIsDisallowed() {
-		ApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
-		context.getBean((Class<?>) null);
-	}
-
 	@Test
 	public void scanAndRefresh() {
 		AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();

spring-context/src/test/java/org/springframework/context/annotation/ConfigurationClassPostProcessorTests.java

@@ -801,6 +801,40 @@ public class ConfigurationClassPostProcessorTests {
 		assertSame(ctx.getBean(BarImpl.class), ctx.getBean(FooImpl.class).bar);
 	}
 
+	@Test
+	public void testCollectionArgumentOnBeanMethod() {
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(CollectionArgumentConfiguration.class, TestBean.class);
+		CollectionArgumentConfiguration bean = ctx.getBean(CollectionArgumentConfiguration.class);
+		assertNotNull(bean.testBeans);
+		assertEquals(1, bean.testBeans.size());
+		assertSame(ctx.getBean(TestBean.class), bean.testBeans.get(0));
+	}
+
+	@Test
+	public void testEmptyCollectionArgumentOnBeanMethod() {
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(CollectionArgumentConfiguration.class);
+		CollectionArgumentConfiguration bean = ctx.getBean(CollectionArgumentConfiguration.class);
+		assertNotNull(bean.testBeans);
+		assertTrue(bean.testBeans.isEmpty());
+	}
+
+	@Test
+	public void testMapArgumentOnBeanMethod() {
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(MapArgumentConfiguration.class, DummyRunnable.class);
+		MapArgumentConfiguration bean = ctx.getBean(MapArgumentConfiguration.class);
+		assertNotNull(bean.testBeans);
+		assertEquals(1, bean.testBeans.size());
+		assertSame(ctx.getBean(Runnable.class), bean.testBeans.values().iterator().next());
+	}
+
+	@Test
+	public void testEmptyMapArgumentOnBeanMethod() {
+		ApplicationContext ctx = new AnnotationConfigApplicationContext(MapArgumentConfiguration.class);
+		MapArgumentConfiguration bean = ctx.getBean(MapArgumentConfiguration.class);
+		assertNotNull(bean.testBeans);
+		assertTrue(bean.testBeans.isEmpty());
+	}
+
 	@Test
 	public void testCollectionInjectionFromSameConfigurationClass() {
 		ApplicationContext ctx = new AnnotationConfigApplicationContext(CollectionInjectionConfiguration.class);
@@ -1564,6 +1598,43 @@ public class ConfigurationClassPostProcessorTests {
 		}
 	}
 
+	public static class DummyRunnable implements Runnable {
+
+		@Override
+		public void run() {
+			/* no-op */
+		}
+	}
+
+	@Configuration
+	static class CollectionArgumentConfiguration {
+
+		List<TestBean> testBeans;
+
+		@Bean(autowireCandidate = false)
+		public TestBean thing(List<TestBean> testBeans) {
+			this.testBeans = testBeans;
+			return new TestBean();
+		}
+	}
+
+	@Configuration
+	public static class MapArgumentConfiguration {
+
+		Map<String, Runnable> testBeans;
+
+		@Bean(autowireCandidate = false)
+		Runnable testBean(Map<String, Runnable> testBeans) {
+			this.testBeans = testBeans;
+			return () -> {};
+		}
+
+		// Unrelated, not to be considered as a factory method
+		private boolean testBean(boolean param) {
+			return param;
+		}
+	}
+
 	@Configuration
 	static class CollectionInjectionConfiguration {