add RepositoryApi.compare(Object projectIdOrPath, String from, String to, Object fromProjectId, boolean straight)

gitlab4j-api/src/main/java/org/gitlab4j/api/RepositoryApi.java

@@ -914,18 +914,7 @@ public File getRepositoryArchive(
      */
     public CompareResults compare(Object projectIdOrPath, String from, String to, boolean straight)
             throws GitLabApiException {
-        Form formData = new GitLabApiForm()
-                .withParam("from", from, true)
-                .withParam("to", to, true)
-                .withParam("straight", straight);
-        Response response = get(
-                Response.Status.OK,
-                formData.asMap(),
-                "projects",
-                getProjectIdOrPath(projectIdOrPath),
-                "repository",
-                "compare");
-        return (response.readEntity(CompareResults.class));
+        return compare(projectIdOrPath, from, to, null, straight);
     }
 
     /**
@@ -942,6 +931,38 @@ public CompareResults compare(Object projectIdOrPath, String from, String to) th
         return (compare(projectIdOrPath, from, to, false));
     }
 
+    /**
+     * Compare branches, tags or commits. This can be accessed without authentication
+     * if the repository is publicly accessible.
+     *
+     * @param projectIdOrPath the project in the form of an Long(ID), String(path), or Project instance
+     * @param from the commit SHA or branch name
+     * @param to the commit SHA or branch name
+     * @param fromProjectId The ID to compare from.
+     * @param straight specifies the comparison method, true for direct comparison between from and to (from..to),
+     *          false to compare using merge base (from…to)
+     * @return a CompareResults containing the results of the comparison
+     * @throws GitLabApiException if any exception occurs
+     */
+    public CompareResults compare(Object projectIdOrPath, String from, String to, Object fromProjectId, boolean straight)
+        throws GitLabApiException {
+        GitLabApiForm formData = new GitLabApiForm()
+            .withParam("from", from, true)
+            .withParam("to", to, true)
+            .withParam("straight", straight);
+        if (fromProjectId != null) {
+            formData.withParam("from_project_id", fromProjectId);
+        }
+        Response response = get(
+            Response.Status.OK,
+            formData.asMap(),
+            "projects",
+            getProjectIdOrPath(projectIdOrPath),
+            "repository",
+            "compare");
+        return (response.readEntity(CompareResults.class));
+    }
+
     /**
      * Get a list of contributors from a project.
      *