code: public DbxEntry./*@Nullable*/Folder createFolder(String path)
          throws DbxException
      {
          DbxPathV1.checkArgNonRoot("path", path);
  
          String[] params = {
              "root", "auto",
              "path", path,
          };
  
          return doPost(host.getApi(), "1/fileops/create_folder", params, null, new DbxRequestUtil.ResponseHandler<DbxEntry./*@Nullable*/Folder>() {
              @Override
              public DbxEntry./*@Nullable*/Folder handle(HttpRequestor.Response response)
                  throws DbxException
              {
                  if (response.getStatusCode() == 403) return null;
                  if (response.getStatusCode() != 200) throw DbxRequestUtil.unexpectedStatus(response);
                  return DbxRequestUtil.readJsonFromResponse(DbxEntry.Folder.Reader, response);
              }
          });
      }
docs: Create a new folder in Dropbox.
  
  @return
  If successful, returns the metadata for the newly created folder, otherwise
  returns {@code null}.