Fix infinite recursion when a @Suggestions method returns a CompletableFuture (#771)

* Fix infinite recursion when a `@Suggestions` method returns a CompletableFuture

* Name future test suggestion source more properly

Author: emilyy-dev

cloud-annotations/src/main/java/org/incendo/cloud/annotations/suggestion/MethodSuggestionProvider.java

@@ -87,7 +87,7 @@ public MethodSuggestionProvider(
     @SuppressWarnings("rawtypes")
     public static @NonNull CompletableFuture<Iterable<@NonNull Suggestion>> mapSuggestions(final @NonNull Object input) {
         if (input instanceof CompletableFuture) {
-            return mapSuggestions((CompletableFuture) input);
+            return mapFuture((CompletableFuture) input);
         }
         return CompletableFuture.completedFuture(mapCompleted(input));
     }

cloud-annotations/src/test/java/org/incendo/cloud/annotations/feature/MethodSuggestionProviderTest.java

@@ -26,6 +26,7 @@
 import java.util.Collections;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.CompletableFuture;
 import java.util.stream.Stream;
 import org.checkerframework.checker.nullness.qual.NonNull;
 import org.incendo.cloud.CommandManager;
@@ -94,6 +95,7 @@ void testSuggestions(final @NonNull Object instance) {
                 named("set source", new TestClassSet()),
                 named("stream source", new TestClassStream()),
                 named("iterable source", new TestClassIterable()),
+                named("list future source", new TestClassFutureList()),
                 named("string list source", new TestClassListString()),
                 named("source with CommandInput injected", new TestClassCommandInput()),
                 named("source with injected value", new TestInjectedValue())
@@ -156,6 +158,17 @@ public static final class TestClassListString {
         }
     }
 
+    public static final class TestClassFutureList {
+
+        @Suggestions("suggestions")
+        public @NonNull CompletableFuture<@NonNull Iterable<@NonNull Suggestion>> suggestions(
+                final @NonNull CommandContext<TestCommandSender> context,
+                final @NonNull String input
+        ) {
+            return CompletableFuture.completedFuture(Collections.singletonList(Suggestion.suggestion("foo")));
+        }
+    }
+
     public static final class TestClassCommandInput {
 
         @Suggestions("suggestions")