public Set<Property> allProperties(){
  Set<Property> properties=new HashSet<Property>();
  for (  Node n : nodes) {
    n.includeProperties(properties);
  }
  return Collections.unmodifiableSet(properties);
}

public Set < Property > allProperties ( ) { Set < Property > properties = new HashSet < Property > ( ) ; for ( Node n : nodes ) { n . includeProperties ( properties ) ; } return Collections . unmodifiableSet ( properties ) ; }
this method returns all properties contained in the node hierarchy that can be used to search for the trace .
