Guard against binding non-instantiable types

Update `JavaBeanBinder` so that null instances that are non-instantiable
are not bound.

Fixes gh-10131

Author: mbhave

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

@@ -168,17 +168,17 @@ public BeanSupplier<T> getSupplier(Bindable<T> target) {
 		}
 
 		@SuppressWarnings("unchecked")
-		public static <T> Bean<T> get(Bindable<T> bindable,
-				boolean useExistingValueForType) {
+		public static <T> Bean<T> get(Bindable<T> bindable, boolean canCallGetValue) {
 			Class<?> type = bindable.getType().resolve();
 			Supplier<T> value = bindable.getValue();
-			if (value == null && !isInstantiable(type)) {
-				return null;
-			}
-			if (useExistingValueForType && value != null) {
-				T instance = value.get();
+			T instance = null;
+			if (canCallGetValue && value != null) {
+				instance = value.get();
 				type = (instance != null ? instance.getClass() : type);
 			}
+			if (instance == null && !isInstantiable(type)) {
+				return null;
+			}
 			Bean<?> bean = Bean.cached;
 			if (bean == null || !type.equals(bean.getType())) {
 				bean = new Bean<>(type);

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

@@ -21,6 +21,8 @@
 import java.util.Collections;
 import java.util.List;
 
+import javax.validation.Validation;
+
 import org.assertj.core.matcher.AssertionMatcher;
 import org.junit.Before;
 import org.junit.Rule;
@@ -30,14 +32,21 @@
 import org.mockito.Answers;
 import org.mockito.InOrder;
 
+import org.springframework.boot.context.properties.bind.validation.ValidationBindHandler;
 import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
 import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
+import org.springframework.boot.context.properties.source.ConfigurationPropertySources;
 import org.springframework.boot.context.properties.source.MockConfigurationPropertySource;
 import org.springframework.core.annotation.AnnotationUtils;
 import org.springframework.core.convert.ConversionFailedException;
+import org.springframework.core.env.PropertySource;
 import org.springframework.core.env.StandardEnvironment;
+import org.springframework.core.io.Resource;
 import org.springframework.format.annotation.DateTimeFormat;
 import org.springframework.test.context.support.TestPropertySourceUtils;
+import org.springframework.validation.Validator;
+import org.springframework.validation.annotation.Validated;
+import org.springframework.validation.beanvalidation.SpringValidatorAdapter;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.hamcrest.Matchers.containsString;
@@ -239,6 +248,20 @@ public void assertion(BindException ex) throws AssertionError {
 		this.binder.bind("foo", target);
 	}
 
+	@Test
+	public void bindToValidatedBeanWithResourceAndNonEnumerablePropertySource() {
+		ConfigurationPropertySources.from(new PropertySource<String>("test") {
+			@Override
+			public Object getProperty(String name) {
+				return null;
+			}
+		}).forEach(this.sources::add);
+		Validator validator = new SpringValidatorAdapter(Validation.byDefaultProvider()
+				.configure().buildValidatorFactory().getValidator());
+		this.binder.bind("foo", Bindable.of(ResourceBean.class),
+				new ValidationBindHandler(validator));
+	}
+
 	public static class JavaBean {
 
 		private String value;
@@ -265,4 +288,19 @@ public enum ExampleEnum {
 
 	}
 
+	@Validated
+	public static class ResourceBean {
+
+		private Resource resource;
+
+		public Resource getResource() {
+			return this.resource;
+		}
+
+		public void setResource(Resource resource) {
+			this.resource = resource;
+		}
+
+	}
+
 }