Allow returning ? extends Suggestion or ? extends Iterable<? extends Suggestion>> from suggestion providers (#690)

Author: jpenilla

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

@@ -77,7 +77,7 @@ void testSuggestions(final @NonNull Object instance) {
         );
 
         // Act
-        final Iterable<Suggestion> suggestions =
+        final Iterable<? extends Suggestion> suggestions =
                 this.commandManager.parserRegistry()
                         .getSuggestionProvider("suggestions")
                         .orElseThrow(NullPointerException::new)

cloud-core/src/main/java/org/incendo/cloud/internal/SuggestionContext.java

@@ -95,7 +95,7 @@ public SuggestionContext(
      *
      * @param suggestions the suggestions to add
      */
-    public void addSuggestions(final @NonNull Iterable<@NonNull Suggestion> suggestions) {
+    public void addSuggestions(final @NonNull Iterable<? extends @NonNull Suggestion> suggestions) {
         suggestions.forEach(this::addSuggestion);
     }
 

cloud-core/src/main/java/org/incendo/cloud/parser/standard/EitherParser.java

@@ -153,7 +153,7 @@ public EitherParser(final @NonNull ParserDescriptor<C, U> primary, final @NonNul
 
     @Override
     @SuppressWarnings({"unchecked", "rawtypes"})
-    public @NonNull CompletableFuture<@NonNull Iterable<@NonNull Suggestion>> suggestionsFuture(
+    public @NonNull CompletableFuture<? extends @NonNull Iterable<? extends @NonNull Suggestion>> suggestionsFuture(
             final @NonNull CommandContext<C> context,
             final @NonNull CommandInput input
     ) {

cloud-core/src/main/java/org/incendo/cloud/suggestion/BlockingSuggestionProvider.java

@@ -57,10 +57,10 @@ interface BlockingSuggestionProvider<C> extends SuggestionProvider<C> {
      * @param input   the current input
      * @return the suggestions
      */
-    @NonNull Iterable<@NonNull Suggestion> suggestions(@NonNull CommandContext<C> context, @NonNull CommandInput input);
+    @NonNull Iterable<? extends @NonNull Suggestion> suggestions(@NonNull CommandContext<C> context, @NonNull CommandInput input);
 
     @Override
-    default @NonNull CompletableFuture<@NonNull Iterable<@NonNull Suggestion>> suggestionsFuture(
+    default @NonNull CompletableFuture<? extends @NonNull Iterable<? extends @NonNull Suggestion>> suggestionsFuture(
             final @NonNull CommandContext<C> context,
             final @NonNull CommandInput input
     ) {

cloud-core/src/main/java/org/incendo/cloud/suggestion/SuggestionProvider.java

@@ -55,7 +55,7 @@ public interface SuggestionProvider<C> {
      * @param input   the current input
      * @return the suggestions
      */
-    @NonNull CompletableFuture<@NonNull Iterable<@NonNull Suggestion>> suggestionsFuture(
+    @NonNull CompletableFuture<? extends @NonNull Iterable<? extends @NonNull Suggestion>> suggestionsFuture(
             @NonNull CommandContext<C> context,
             @NonNull CommandInput input
     );
@@ -132,7 +132,7 @@ static <C> SuggestionProvider<C> noSuggestions() {
      * @return suggestion provider
      */
     static <C> @NonNull SuggestionProvider<C> suggesting(
-            final @NonNull Iterable<@NonNull Suggestion> suggestions
+            final @NonNull Iterable<? extends @NonNull Suggestion> suggestions
     ) {
         return blocking((ctx, input) -> suggestions);
     }

cloud-core/src/test/java/org/incendo/cloud/parser/aggregate/AggregateParserTest.java

@@ -143,7 +143,7 @@ void testSuggestionsFirstArgument() {
                 .build();
 
         // Act
-        final Iterable<Suggestion> suggestions = parser.suggestionProvider()
+        final Iterable<? extends Suggestion> suggestions = parser.suggestionProvider()
                 .suggestionsFuture(this.commandContext, CommandInput.empty()).join();
 
         // Assert
@@ -172,7 +172,7 @@ void testSuggestionsSecondArgument() {
                 .build();
 
         // Act
-        final Iterable<Suggestion> suggestions = parser.suggestionProvider()
+        final Iterable<? extends Suggestion> suggestions = parser.suggestionProvider()
                 .suggestionsFuture(this.commandContext, CommandInput.of("123 ")).join();
 
         // Assert

cloud-core/src/test/java/org/incendo/cloud/parser/standard/EitherParserTest.java

@@ -93,7 +93,7 @@ void testParsingFailing() {
     @Test
     void testSuggestions() {
         // Act
-        final Iterable<Suggestion> suggestions = this.parser.suggestionsFuture(this.context, CommandInput.empty()).join();
+        final Iterable<? extends Suggestion> suggestions = this.parser.suggestionsFuture(this.context, CommandInput.empty()).join();
 
         // Assert
         assertThat(suggestions).containsExactly(