public MetadataGraphVertex getSource() {
        return source;
    }

    public void setSource(MetadataGraphVertex source) {
        this.source = source;
    }

    public MetadataGraphVertex getTarget() {
        return target;
    }

    public void setTarget(MetadataGraphVertex target) {
        this.target = target;
    }

    @Override
    public String toString() {