public Set<String> keySet() {
        Set<String> keys = new HashSet<String>();
        for (PathSignature path : pathToIndex.keySet())
            keys.add(path.toString());
        return keys;
    }
public Set < String > keySet ( ) { Set < String > keys = new HashSet < String > ( ) ; for ( PathSignature path : pathToIndex . keySet ( ) ) keys . add ( path . toString ( ) ) ; return keys ; }
Returns the set of keys known by this {@link BasisMapping}