DATACMNS-829 - Fixed handling of Map null values in ProxyProjectionFactory.

We now eagerly return null values in attempts to project Map values.

Author: odrotbohm

src/main/java/org/springframework/data/projection/ProjectingMethodInterceptor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2015 the original author or authors.
+ * Copyright 2014-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -137,7 +137,7 @@ private Map<Object, Object> projectMapValues(Map<?, ?> sources, TypeInformation<
 	}
 
 	private Object getProjection(Object result, Class<?> returnType) {
-		return ClassUtils.isAssignable(returnType, result.getClass()) ? result
+		return result == null || ClassUtils.isAssignable(returnType, result.getClass()) ? result
 				: factory.createProjection(returnType, result);
 	}
 

src/test/java/org/springframework/data/projection/ProxyProjectionFactoryUnitTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2014-2015 the original author or authors.
+ * Copyright 2014-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -20,6 +20,7 @@
 
 import java.beans.PropertyDescriptor;
 import java.lang.reflect.Proxy;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -159,7 +160,7 @@ public void returnsAllPropertiesAsInputProperties() {
 		ProjectionInformation projectionInformation = factory.getProjectionInformation(CustomerExcerpt.class);
 		List<PropertyDescriptor> result = projectionInformation.getInputProperties();
 
-		assertThat(result, hasSize(5));
+		assertThat(result, hasSize(6));
 	}
 
 	/**
@@ -247,13 +248,30 @@ public void exposesProjectionInformationCorrectly() {
 		assertThat(information.isClosed(), is(true));
 	}
 
+	/**
+	 * @see DATACMNS-829
+	 */
+	@Test
+	public void projectsMapOfStringToObjectCorrectly() {
+
+		Customer customer = new Customer();
+		customer.data = Collections.singletonMap("key", null);
+
+		Map<String, Object> data = factory.createProjection(CustomerExcerpt.class, customer).getData();
+
+		assertThat(data, is(notNullValue()));
+		assertThat(data.containsKey("key"), is(true));
+		assertThat(data.get("key"), is(nullValue()));
+	}
+
 	static class Customer {
 
 		public Long id;
 		public String firstname, lastname;
 		public Address address;
 		public byte[] picture;
 		public Address[] shippingAddresses;
+		public Map<String, Object> data;
 	}
 
 	static class Address {
@@ -272,6 +290,8 @@ interface CustomerExcerpt {
 		AddressExcerpt[] getShippingAddresses();
 
 		byte[] getPicture();
+
+		Map<String, Object> getData();
 	}
 
 	interface AddressExcerpt {