boolean function ( ) { return ( ( sourceNode != null ) && ( destinationNode != null ) ) ; }
validate this edge . checks if source and destination are non-null . concode_field_sep Node sourceNode concode_elem_sep String id concode_elem_sep Node destinationNode concode_field_sep void setSource concode_elem_sep void print concode_elem_sep Node getDestination concode_elem_sep Node getSource concode_elem_sep void setDestination