RXJava2 3 Threads at 1 time

/* Java 3 observable calls at once */
        return Observable.zip(
                getApps,
                getInternalStorage(),
                getExternal(),
                new Function3<AllAppsStorageData, StorageFiles, ExternalStorageFiles, StorageFilesAndDetails>()
                {
                    @Override
                    public StorageFilesAndDetails apply(AllAppsStorageData allAppsStorageData, StorageFiles internalStorageFiles, ExternalStorageFiles externalStorageFiles)
                    {
                        StorageFilesAndDetails storageFilesAndDetails;


                        if(externalStorageFiles.isHasExternal())
                        {
                            storageFilesAndDetails = new StorageFilesAndDetails(internalStorageFiles,externalStorageFiles,allAppsStorageData);
                        }
                        else
                        {
                            storageFilesAndDetails = new StorageFilesAndDetails(internalStorageFiles,allAppsStorageData);
                        }

                        return storageFilesAndDetails;
                    }
                }
        );