Corrected fallback handling for existing cases

Author: itzg

src/main/java/me/itzg/helpers/modrinth/ModrinthApiClient.java

@@ -183,11 +183,13 @@ public Mono<List<Version>> getVersionsForProject(String projectIdOrSlug,
                                                      @Nullable Loader loader, String gameVersion
     ) {
         return getJustVersionsForProject(projectIdOrSlug, gameVersion,
-            loader != null ? Collections.singletonList(loader.toString()) : null
+            loader != null ? Collections.singletonList(loader.toString()) : null,
+            false
         )
             .switchIfEmpty(
                 getJustVersionsForProject(projectIdOrSlug, gameVersion,
-                    expandCompatibleLoaders(loader)
+                    expandCompatibleLoaders(loader),
+                    true
                 )
             )
             .switchIfEmpty(
@@ -199,11 +201,13 @@ public Mono<List<Version>> getVersionsForProject(String projectIdOrSlug,
     /**
      * @return the non-empty list of versions or an empty mono
      */
-    private Mono<List<Version>> getJustVersionsForProject(String projectIdOrSlug, String gameVersion,
-        Collection<String> loaderNames
+    private Mono<List<Version>> getJustVersionsForProject(
+        String projectIdOrSlug, String gameVersion,
+        Collection<String> loaderNames,
+        boolean skipEmptyLoaders
     ) {
         return
-            loaderNames == null || loaderNames.isEmpty() ?
+            skipEmptyLoaders && (loaderNames == null || loaderNames.isEmpty()) ?
                 Mono.empty() :
                 sharedFetch.fetch(
                         uriBuilder.resolve("/v2/project/{id|slug}/version",

src/test/java/me/itzg/helpers/modrinth/ModrinthCommandTest.java

@@ -14,8 +14,8 @@
 import com.github.tomakehurst.wiremock.extension.responsetemplating.ResponseTemplateTransformer;
 import com.github.tomakehurst.wiremock.junit5.WireMockExtension;
 import com.github.tomakehurst.wiremock.matching.RequestPatternBuilder;
-import java.nio.file.Path;
 import java.nio.file.Files;
+import java.nio.file.Path;
 import java.util.Arrays;
 import java.util.function.Consumer;
 import me.itzg.helpers.LatchingExecutionExceptionHandler;
@@ -167,7 +167,8 @@ void failsWhenNoDependenciesForModLoader(@TempDir Path tempDir) throws JsonProce
                 .put("project_id", requiredDepProjectId)
                 .put("dependency_type", "required");
         });
-        stubVersionRequestEmptyResponse(requiredDepProjectId);
+        stubVersionRequestEmptyResponse(requiredDepProjectId, "paper");
+        stubVersionRequestEmptyResponse(requiredDepProjectId, "spigot");
         stubGetProject(requiredDepProjectId, new Project().setProjectType(ProjectType.resourcepack));
 
         stubDownload();
@@ -462,7 +463,7 @@ private void stubVersionRequest(String projectId, String versionId, Consumer<Arr
         depsAdder.accept(dependenciesArray);
 
         stubFor(get(urlPathEqualTo("/v2/project/" + projectId + "/version"))
-            .withQueryParam("loaders", equalTo("[\"paper\",\"spigot\"]"))
+            .withQueryParam("loaders", equalTo("[\"paper\"]"))
             .withQueryParam("game_versions", equalTo("[\"1.21.1\"]"))
             .willReturn(aResponse()
                 .withHeader("Content-Type", "application/json")
@@ -471,11 +472,11 @@ private void stubVersionRequest(String projectId, String versionId, Consumer<Arr
         );
     }
 
-    private void stubVersionRequestEmptyResponse(String projectId) {
+    private void stubVersionRequestEmptyResponse(String projectId, String loader) {
         final ArrayNode versionResp = objectMapper.createArrayNode();
 
         stubFor(get(urlPathEqualTo("/v2/project/" + projectId + "/version"))
-            .withQueryParam("loaders", equalTo("[\"paper\",\"spigot\"]"))
+            .withQueryParam("loaders", equalTo("[\"" + loader + "\"]"))
             .withQueryParam("game_versions", equalTo("[\"1.21.1\"]"))
             .willReturn(aResponse()
                 .withHeader("Content-Type", "application/json")