Improve union support of SchemaMappingInspector

If the union controller method returns Object, as a fallback try the package of the controller. See gh-960

Author: rstoyanchev

spring-graphql/src/main/java/org/springframework/graphql/execution/SchemaMappingInspector.java

@@ -49,6 +49,7 @@
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.beans.BeansException;
+import org.springframework.core.MethodParameter;
 import org.springframework.core.ReactiveAdapter;
 import org.springframework.core.ReactiveAdapterRegistry;
 import org.springframework.core.ResolvableType;
@@ -522,6 +523,13 @@ private static void addReflectionClassResolver(
 int index = clazz.getName().indexOf(clazz.getSimpleName());
 resolver.addClassPrefix(outputTypeName, clazz.getName().substring(0, index));
 }
+else if (fieldEntry.getValue() instanceof SelfDescribingDataFetcher<?> sddf) {
+if (sddf.getReturnType().getSource() instanceof MethodParameter param) {
+clazz = param.getDeclaringClass();
+int index = clazz.getName().indexOf(clazz.getSimpleName());
+resolver.addClassPrefix(outputTypeName, clazz.getName().substring(0, index));
+}
+}
 }
 }
 }

spring-graphql/src/test/java/org/springframework/graphql/execution/SchemaMappingInspectorUnionTests.java

@@ -51,7 +51,7 @@ public class SchemaMappingInspectorUnionTests extends SchemaMappingInspectorTest
 class InterfaceFieldsNotOnJavaInterface {
 
 @Test
-void reportUnmappedFields() {
+void reportUnmappedFieldsByCheckingReturnTypePackage() {
 SchemaReport report = inspectSchema(schema, SearchController.class);
 assertThatReport(report)
 .hasSkippedTypeCount(0)
@@ -60,6 +60,16 @@ void reportUnmappedFields() {
 .containsUnmappedFields("Video", "title");
 }
 
+@Test
+void reportUnmappedFieldsByCheckingControllerTypePackage() {
+SchemaReport report = inspectSchema(schema, ObjectSearchController.class);
+assertThatReport(report)
+.hasSkippedTypeCount(0)
+.hasUnmappedFieldCount(3)
+.containsUnmappedFields("Photo", "height", "width")
+.containsUnmappedFields("Video", "title");
+}
+
 
 sealed interface ResultItem permits Photo, Video { }
 record Photo() implements ResultItem { }
@@ -73,6 +83,16 @@ List<ResultItem> search() {
 throw new UnsupportedOperationException();
 }
 }
+
+
+@Controller
+static class ObjectSearchController {
+
+@QueryMapping
+List<Object> search() {
+throw new UnsupportedOperationException();
+}
+}
 }