DATAREST-977 - Fixed reading of complex enums on collection expansion for PATCH.

When merging collections on PATCH we now don't use the first collection item's type for all elements but inspect the values for each existing element found. When it comes to appending elements to the collection, wen now just stick to the declared component type as type hint for reading the provided value.

spring-data-rest-webmvc/src/test/java/org/springframework/data/rest/webmvc/json/DomainObjectReaderUnitTests.java

@@ -15,7 +15,7 @@
  */
 package org.springframework.data.rest.webmvc.json;
 
-import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.Matchers.*;
 import static org.junit.Assert.*;
 import static org.mockito.Mockito.*;
 
@@ -93,6 +93,7 @@ public class DomainObjectReaderUnitTests {
 		mappingContext.getPersistentEntity(Parent.class);
 		mappingContext.getPersistentEntity(Product.class);
 		mappingContext.getPersistentEntity(TransientReadOnlyProperty.class);
+		mappingContext.getPersistentEntity(CollectionOfEnumWithMethods.class);
 		mappingContext.afterPropertiesSet();
 
 		PersistentEntities entities = new PersistentEntities(Collections.singleton(mappingContext));
@@ -451,6 +452,20 @@ public class DomainObjectReaderUnitTests {
 		reader.readPut((ObjectNode) node, new TransientReadOnlyProperty(), mapper);
 	}
 
+	@Test // DATAREST-977
+	public void readsCollectionOfComplexEnum() throws Exception {
+
+		CollectionOfEnumWithMethods sample = new CollectionOfEnumWithMethods();
+		sample.enums.add(SampleEnum.FIRST);
+
+		ObjectMapper mapper = new ObjectMapper();
+		JsonNode node = mapper.readTree("{ \"enums\" : [ \"SECOND\", \"FIRST\" ] }");
+
+		CollectionOfEnumWithMethods result = reader.merge((ObjectNode) node, sample, mapper);
+
+		assertThat(result.enums, contains(SampleEnum.SECOND, SampleEnum.FIRST));
+	}
+
 	@SuppressWarnings("unchecked")
 	private static <T> T as(Object source, Class<T> type) {
 
@@ -585,4 +600,33 @@ public class DomainObjectReaderUnitTests {
 
 		public void setName(String name) {}
 	}
+
+	// DATAREST-977
+
+	interface EnumInterface {
+		String getFoo();
+	}
+
+	static enum SampleEnum implements EnumInterface {
+
+		FIRST {
+
+			@Override
+			public String getFoo() {
+				return "first";
+			}
+
+		},
+		SECOND {
+
+			public String getFoo() {
+				return "second";
+			}
+		};
+	}
+
+	@JsonAutoDetect(fieldVisibility = Visibility.ANY)
+	static class CollectionOfEnumWithMethods {
+		List<SampleEnum> enums = new ArrayList<SampleEnum>();
+	}
 }