Fix dropping of extensions in ContextDataFetcherDecorator

ContextDataFetcherDecorator was not retaining extensions for DataFetchers returning
a DataFetcherResult instance.

Closes gh-1199

Signed-off-by: Patrick Strawderman <pstrawderman@netflix.com>
[brian.clozel@broadcom.com: apply code conventions]
Signed-off-by: Brian Clozel <brian.clozel@broadcom.com>

Author: kilink

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

@@ -87,11 +87,7 @@ public Object get(DataFetchingEnvironment env) throws Exception {
 		Object value = snapshot.wrap(() -> this.delegate.get(env)).call();
 
 		if (value instanceof DataFetcherResult<?> dataFetcherResult) {
-			Object adapted = updateValue(dataFetcherResult.getData(), snapshot, graphQlContext);
-			value = DataFetcherResult.newResult()
-					.data(adapted)
-					.errors(dataFetcherResult.getErrors())
-					.localContext(dataFetcherResult.getLocalContext()).build();
+			value = dataFetcherResult.map((data) -> updateValue(data, snapshot, graphQlContext));
 		}
 		else {
 			value = updateValue(value, snapshot, graphQlContext);

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

@@ -19,6 +19,7 @@
 import java.time.Duration;
 import java.util.Collections;
 import java.util.List;
+import java.util.Map;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.function.BiConsumer;
@@ -347,4 +348,20 @@ void cancelFluxDataFetcherSubscriptionWhenRequestCancelled() throws Exception {
 		assertThat(dataFetcherCancelled).isTrue();
 	}
 
+	@Test
+	void testExtensionsAreRetained() throws Exception {
+		GraphQL graphQl = GraphQlSetup.schemaContent(SCHEMA_CONTENT)
+				.queryFetcher("greeting", (env) ->
+						DataFetcherResult.newResult().data("Hello")
+								.extensions(Map.of("foo", "bar")).build())
+				.toGraphQl();
+
+		ExecutionInput input = ExecutionInput.newExecutionInput().query("{ greeting }").build();
+		ExecutionResult executionResult = graphQl.executeAsync(input).get();
+
+		String greeting = ResponseHelper.forResult(executionResult).toEntity("greeting", String.class);
+		assertThat(greeting).isEqualTo("Hello");
+
+		assertThat(executionResult.getExtensions()).containsEntry("foo", "bar");
+	}
 }