Fallback to Object.class if ResolvableType can't resolve

Fixes gh-11908

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

@@ -262,7 +262,7 @@ public class Binder {
 	}
 
 	private AggregateBinder<?> getAggregateBinder(Bindable<?> target, Context context) {
-		Class<?> resolvedType = target.getType().resolve();
+		Class<?> resolvedType = target.getType().resolve(Object.class);
 		if (Map.class.isAssignableFrom(resolvedType)) {
 			return new MapBinder(context);
 		}
@@ -312,7 +312,7 @@ public class Binder {
 		}
 		BeanPropertyBinder propertyBinder = (propertyName, propertyTarget) -> bind(
 				name.append(propertyName), propertyTarget, handler, context, false);
-		Class<?> type = target.getType().resolve();
+		Class<?> type = target.getType().resolve(Object.class);
 		if (!allowRecursiveBinding && context.hasBoundBean(type)) {
 			return null;
 		}
@@ -330,7 +330,7 @@ public class Binder {
 			// We know there are properties to bind so we can't bypass anything
 			return false;
 		}
-		Class<?> resolved = target.getType().resolve();
+		Class<?> resolved = target.getType().resolve(Object.class);
 		if (resolved.isPrimitive() || NON_BEAN_CLASSES.contains(resolved)) {
 			return true;
 		}

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

@@ -38,7 +38,7 @@ class CollectionBinder extends IndexedElementsBinder<Collection<Object>> {
 	@Override
 	protected Object bindAggregate(ConfigurationPropertyName name, Bindable<?> target,
 			AggregateElementBinder elementBinder) {
-		Class<?> collectionType = (target.getValue() == null ? target.getType().resolve()
+		Class<?> collectionType = (target.getValue() == null ? target.getType().resolve(Object.class)
 				: List.class);
 		ResolvableType aggregateType = forClassWithGenerics(List.class,
 				target.getType().asCollection().getGenerics());

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

@@ -150,7 +150,7 @@ abstract class IndexedElementsBinder<T> extends AggregateBinder<T> {
 			ResolvableType... generics) {
 		ResolvableType[] resolvedGenerics = new ResolvableType[generics.length];
 		for (int i = 0; i < generics.length; i++) {
-			resolvedGenerics[i] = forClassWithGenerics(generics[i].resolve(),
+			resolvedGenerics[i] = forClassWithGenerics(generics[i].resolve(Object.class),
 					generics[i].getGenerics());
 		}
 		return ResolvableType.forClassWithGenerics(type, resolvedGenerics);

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

@@ -54,7 +54,7 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 	protected Object bindAggregate(ConfigurationPropertyName name, Bindable<?> target,
 			AggregateElementBinder elementBinder) {
 		Map<Object, Object> map = CollectionFactory.createMap(
-				(target.getValue() == null ? target.getType().resolve() : Map.class), 0);
+				(target.getValue() == null ? target.getType().resolve(Object.class) : Map.class), 0);
 		Bindable<?> resolvedTarget = resolveTarget(target);
 		boolean hasDescendants = getContext().streamSources().anyMatch((source) -> source
 				.containsDescendantOf(name) == ConfigurationPropertyState.PRESENT);
@@ -75,7 +75,7 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 	}
 
 	private Bindable<?> resolveTarget(Bindable<?> target) {
-		Class<?> type = target.getType().resolve();
+		Class<?> type = target.getType().resolve(Object.class);
 		if (Properties.class.isAssignableFrom(type)) {
 			return STRING_STRING_MAP;
 		}
@@ -132,7 +132,7 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 
 		private ConfigurationPropertyName getEntryName(ConfigurationPropertySource source,
 				ConfigurationPropertyName name) {
-			Class<?> resolved = this.valueType.resolve();
+			Class<?> resolved = this.valueType.resolve(Object.class);
 			if (Collection.class.isAssignableFrom(resolved) || this.valueType.isArray()) {
 				return chopNameAtNumericIndex(name);
 			}
@@ -161,7 +161,7 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 
 		private boolean isScalarValue(ConfigurationPropertySource source,
 				ConfigurationPropertyName name) {
-			Class<?> resolved = this.valueType.resolve();
+			Class<?> resolved = this.valueType.resolve(Object.class);
 			String packageName = ClassUtils.getPackageName(resolved);
 			if (!packageName.startsWith("java.lang") && !resolved.isEnum()) {
 				return false;

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

@@ -280,6 +280,15 @@ public class BinderTests {
 		this.binder.bind("foo", target);
 	}
 
+	@Test
+	public void bindToBeanWithUnresolvableGenerics() {
+		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
+		source.put("foo.bar", "hello");
+		this.sources.add(source);
+		Bindable<GenericBean> target = Bindable.of(GenericBean.class);
+		this.binder.bind("foo", target);
+	}
+
 	public static class JavaBean {
 
 		private String value;
@@ -349,4 +358,18 @@ public class BinderTests {
 
 	}
 
+	public static class GenericBean<T> {
+
+		private T bar;
+
+
+		public T getBar() {
+			return this.bar;
+		}
+
+		public void setBar(T bar) {
+			this.bar = bar;
+		}
+	}
+
 }