code: public WorkspaceFolderContents listWorkspaceFolderItems(String accountId, String workspaceId, String folderId) throws ApiException {
      return listWorkspaceFolderItems(accountId, workspaceId, folderId, null);
    }
docs: List Workspace Folder Contents
  Retrieves workspace folder contents, which can include sub folders and files.
  @param accountId The external account number (int) or account ID Guid. (required)
  @param workspaceId Specifies the workspace ID GUID. (required)
  @param folderId The ID of the folder being accessed. (required)
  @return WorkspaceFolderContents