From a946d651ffbc72879a52dc0b593861251376b547 Mon Sep 17 00:00:00 2001
From: Oliver Gierke <ogierke@pivotal.io>
Date: Fri, 23 Dec 2016 12:53:36 +0100
Subject: [PATCH] DATACMNS-967 - Getters that are default methods are not
 considered projection input properties anymore.

We now exclude getter methods that are default methods from the consideration which properties of a projection interface are considered input properties in the first place.

Some additional Java 8 polish in DefaultProjectionInformation.
---
 .../DefaultProjectionInformation.java         | 31 +++++++++++------
 .../SpelAwareProxyProjectionFactory.java      |  4 +++
 ...DefaultProjectionInformationUnitTests.java | 33 ++++++++++++++-----
 3 files changed, 50 insertions(+), 18 deletions(-)

diff --git a/src/main/java/org/springframework/data/projection/DefaultProjectionInformation.java b/src/main/java/org/springframework/data/projection/DefaultProjectionInformation.java
index 4cb6adb28..c72b95cfa 100644
--- a/src/main/java/org/springframework/data/projection/DefaultProjectionInformation.java
+++ b/src/main/java/org/springframework/data/projection/DefaultProjectionInformation.java
@@ -16,9 +16,11 @@
 package org.springframework.data.projection;
 
 import java.beans.PropertyDescriptor;
+import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.util.Assert;
@@ -63,15 +65,9 @@ class DefaultProjectionInformation implements ProjectionInformation {
 	 */
 	public List<PropertyDescriptor> getInputProperties() {
 
-		List<PropertyDescriptor> result = new ArrayList<PropertyDescriptor>();
-
-		for (PropertyDescriptor descriptor : properties) {
-			if (isInputProperty(descriptor)) {
-				result.add(descriptor);
-			}
-		}
-
-		return result;
+		return properties.stream()//
+				.filter(it -> isInputProperty(it))//
+				.collect(Collectors.toList());
 	}
 
 	/* 
@@ -104,7 +100,10 @@ class DefaultProjectionInformation implements ProjectionInformation {
 	private static List<PropertyDescriptor> collectDescriptors(Class<?> type) {
 
 		List<PropertyDescriptor> result = new ArrayList<PropertyDescriptor>();
-		result.addAll(Arrays.asList(BeanUtils.getPropertyDescriptors(type)));
+
+		result.addAll(Arrays.stream(BeanUtils.getPropertyDescriptors(type))//
+				.filter(it -> !hasDefaultGetter(it))//
+				.collect(Collectors.toList()));
 
 		for (Class<?> interfaze : type.getInterfaces()) {
 			result.addAll(collectDescriptors(interfaze));
@@ -112,4 +111,16 @@ class DefaultProjectionInformation implements ProjectionInformation {
 
 		return result;
 	}
+
+	/**
+	 * Returns whether the given {@link PropertyDescriptor} has a getter that is a Java 8 default method.
+	 * 
+	 * @param descriptor must not be {@literal null}.
+	 * @return
+	 */
+	private static boolean hasDefaultGetter(PropertyDescriptor descriptor) {
+
+		Method method = descriptor.getReadMethod();
+		return method == null ? false : method.isDefault();
+	}
 }
diff --git a/src/main/java/org/springframework/data/projection/SpelAwareProxyProjectionFactory.java b/src/main/java/org/springframework/data/projection/SpelAwareProxyProjectionFactory.java
index 91fa404c5..5493d5e4d 100644
--- a/src/main/java/org/springframework/data/projection/SpelAwareProxyProjectionFactory.java
+++ b/src/main/java/org/springframework/data/projection/SpelAwareProxyProjectionFactory.java
@@ -96,6 +96,10 @@ public class SpelAwareProxyProjectionFactory extends ProxyProjectionFactory impl
 			@Override
 			protected boolean isInputProperty(PropertyDescriptor descriptor) {
 
+				if (!super.isInputProperty(descriptor)) {
+					return false;
+				}
+
 				Method readMethod = descriptor.getReadMethod();
 
 				if (readMethod == null) {
diff --git a/src/test/java/org/springframework/data/projection/DefaultProjectionInformationUnitTests.java b/src/test/java/org/springframework/data/projection/DefaultProjectionInformationUnitTests.java
index e12979e64..ffa557c07 100644
--- a/src/test/java/org/springframework/data/projection/DefaultProjectionInformationUnitTests.java
+++ b/src/test/java/org/springframework/data/projection/DefaultProjectionInformationUnitTests.java
@@ -19,8 +19,8 @@ import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 
 import java.beans.PropertyDescriptor;
-import java.util.ArrayList;
 import java.util.List;
+import java.util.stream.Collectors;
 
 import org.junit.Test;
 
@@ -53,15 +53,23 @@ public class DefaultProjectionInformationUnitTests {
 		assertThat(toNames(information.getInputProperties()), hasItems("age", "firstname", "lastname"));
 	}
 
+	/**
+	 * @see DATACMNS-967
+	 */
+	@Test
+	public void doesNotConsiderDefaultMethodInputProperties() throws Exception {
+
+		ProjectionInformation information = new DefaultProjectionInformation(WithDefaultMethod.class);
+
+		assertThat(information.isClosed(), is(true));
+		assertThat(toNames(information.getInputProperties()), hasItems("firstname"));
+	}
+
 	private static List<String> toNames(List<PropertyDescriptor> descriptors) {
 
-		List<String> names = new ArrayList<String>(descriptors.size());
-
-		for (PropertyDescriptor descriptor : descriptors) {
-			names.add(descriptor.getName());
-		}
-
-		return names;
+		return descriptors.stream()//
+				.map(it -> it.getName())//
+				.collect(Collectors.toList());
 	}
 
 	interface CustomerProjection {
@@ -75,4 +83,13 @@ public class DefaultProjectionInformationUnitTests {
 
 		int getAge();
 	}
+
+	interface WithDefaultMethod {
+
+		String getFirstname();
+
+		default String getLastname() {
+			return null;
+		}
+	}
 }