final StringBuilder result = new StringBuilder();
final Iterator<OrPart> orIt = tree.iterator();
while(orIt.hasNext()) {
final OrPart orPart = orIt.next();
final Iterator<Part> partIt = orPart.iterator();
while(partIt.hasNext()) {
final Part part = partIt.next();
result.append(" " + part.getProperty().getSegment() + " ");
result.append(convertOperator(part.getType()));