code: private File findPathResource(@NonNull String httpPath) {
          if ("/".equals(httpPath)) {
              File root = new File(mRootPath);
              return root.exists() ? root : null;
          } else {
              File sourceFile = new File(mRootPath, httpPath);
              if (sourceFile.exists()) {
                  return sourceFile;
              }
          }
          return null;
      }
docs: Find the path specified resource.
  
  @param httpPath path.
  
  @return return if the file is found.