code: protected Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource, String subPattern)
          throws IOException {
  
          File rootDir;
          try {
              rootDir = rootDirResource.getFile().getAbsoluteFile();
          } catch (IOException ex) {
              return Collections.emptySet();
          }
          return doFindMatchingFileSystemResources(rootDir, subPattern);
      }
docs: Find all resources in the file system that match the given location pattern
  via the Ant-style PathMatcher.
  
  @param rootDirResource the root directory as Resource
  @param subPattern      the sub pattern to match (below the root directory)
  @return the Set of matching Resource instances
  @throws IOException in case of I/O errors
  @see #retrieveMatchingFiles