Ensure that DataLoader are retrieved from DataFetchingEnvironment

Closes gh-1177

Author: bclozel

Diff for: spring-graphql/src/main/java/org/springframework/graphql/data/method/annotation/support/AnnotatedControllerConfigurer.java

@@ -606,7 +606,7 @@ public ResolvableType getReturnType() {
 
 		@Override
 		public Object get(DataFetchingEnvironment env) {
-			DataLoader<?, ?> dataLoader = env.getDataLoaderRegistry().getDataLoader(this.dataLoaderKey);
+			DataLoader<?, ?> dataLoader = env.getDataLoader(this.dataLoaderKey);
 			Assert.state(dataLoader != null, "No DataLoader for key '" + this.dataLoaderKey + "'");
 			return ((env.getLocalContext() != null) ?
 					dataLoader.load(env.getSource(), env.getLocalContext()) :