code: func findSource(goPath string, filePath string) ([]*Descriptor, error) {
  	var descriptors []*Descriptor
  	err := filepath.Walk(filePath,
  		func(path string, fileInfo os.FileInfo, err error) error {
  			if err != nil {
  				return err
  			}
  			if fileInfo.Mode().IsRegular() && isSource(path) {
  				relPath, err := filepath.Rel(goPath, path)
  				if err != nil {
  					return err
  				}
  				if strings.Contains(relPath, "/META-INF/") {
  					relPath = relPath[strings.Index(relPath, "/META-INF/")+1:]
  				}
  				descriptors = append(descriptors, &Descriptor{name: relPath, fqp: path})
  			}
  			return nil
  
  		})
  
  	return descriptors, err
  }
docs: // -------------------------------------------------------------------------
  // findSource(goPath, filePath)
  // -------------------------------------------------------------------------
  // Given an input 'filePath', recursively parse the filesystem for any files
  // that fit the criteria for being valid golang source (ISREG + (*.(go|c|h)))
  // As a convenience, we also formulate a tar-friendly "name" for each file
  // based on relative position to 'goPath'.
  // -------------------------------------------------------------------------