DATACMNS-1299 - QueryExecutionsConverters now don't unwrap custom Iterable implementations.

Instead of a simple check for assignability from Iterable, we now properly use TypeInformation.isCollectionLike(), which checks for Iterable equality or assignability of collections or arrays as well as an explicit check for Slice as that is needed to properly unwrap Page instances and Slices themselves. That prevents custom domain types implementing Iterable from being unwrapped into their element types.

src/main/java/org/springframework/data/repository/util/QueryExecutionConverters.java

@@ -253,7 +253,8 @@ public abstract class QueryExecutionConverters {
 
 		Class<?> rawType = type.getType();
 
-		boolean needToUnwrap = Iterable.class.isAssignableFrom(rawType) //
+		boolean needToUnwrap = type.isCollectionLike() //
+				|| Slice.class.isAssignableFrom(rawType) //
 				|| rawType.isArray() //
 				|| supports(rawType) //
 				|| org.springframework.data.util.ReflectionUtils.isJava8StreamType(rawType);

src/test/java/org/springframework/data/repository/core/support/AbstractRepositoryMetadataUnitTests.java

@@ -101,6 +101,16 @@ public class AbstractRepositoryMetadataUnitTests {
 		assertThat(metadata.getReturnedDomainClass(method), is(typeCompatibleWith(User.class)));
 	}
 
+	@Test // DATACMNS-1299
+	public void doesNotUnwrapCustomTypeImplementingIterable() throws Exception {
+
+		RepositoryMetadata metadata = AbstractRepositoryMetadata.getMetadata(ContainerRepository.class);
+
+		Method method = ContainerRepository.class.getMethod("someMethod");
+
+		assertThat(metadata.getReturnedDomainClass(method), is(typeCompatibleWith(Container.class)));
+	}
+
 	interface UserRepository extends Repository<User, Long> {
 
 		User findSingle();
@@ -148,4 +158,13 @@ public class AbstractRepositoryMetadataUnitTests {
 		}
 	}
 
+	// DATACMNS-1299
+
+	class Element {}
+
+	abstract class Container implements Iterable<Element> {}
+
+	interface ContainerRepository extends Repository<Container, Long> {
+		Container someMethod();
+	}
 }

src/test/java/org/springframework/data/repository/util/QueryExecutionConvertersUnitTests.java

@@ -40,6 +40,8 @@ import org.junit.Test;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.data.domain.Page;
 import org.springframework.data.domain.Slice;
+import org.springframework.data.util.ClassTypeInformation;
+import org.springframework.data.util.TypeInformation;
 import org.springframework.util.ReflectionUtils;
 import org.springframework.util.concurrent.ListenableFuture;
 
@@ -341,6 +343,21 @@ public class QueryExecutionConvertersUnitTests {
 				is(instanceOf(javaslang.collection.Set.class)));
 	}
 
+	@Test // DATACMNS-1299
+	public void unwrapsPages() throws Exception {
+
+		Method method = Sample.class.getMethod("pages");
+		TypeInformation<Object> returnType = ClassTypeInformation.fromReturnTypeOf(method);
+
+		assertThat(QueryExecutionConverters.unwrapWrapperTypes(returnType), //
+				is((TypeInformation) ClassTypeInformation.from(String.class)));
+	}
+
+	interface Sample {
+
+		Page<String> pages();
+	}
+
 	// Vavr
 
 	@SuppressWarnings("unchecked")