public Stream<RAW> getUnmatchedRaws() {
    return raws.stream().filter(raw -> !rawToBase.containsKey(raw));
  }
public Stream < RAW > getUnmatchedRaws ( ) { return raws . stream ( ) . filter ( raw -> ! rawToBase . containsKey ( raw ) ) ; }
Returns an Iterable to be traversed when matching issues. That means
that the traversal does not fail if method {@link #match(Trackable, Trackable)}
is called.