 using name.atlas and name.png from the AssetManager.
          // The function passed to TextureAtlas is used to resolve relative paths.
          atlas = assetManager.require(atlasFile);

          // Create a AtlasAttachmentLoader that resolves region, mesh, boundingbox and path attachments
          atlasLoader = new spine.AtlasAttachmentLoader(atlas);

          // Create a SkeletonJson instance for parsing the .json file.
          let skeletonJson = new spine.SkeletonJson(atlasLoader);

          // 