src/main/java/org/helm/notation2/parser/notation/connection/ConnectionNotation.java
public String toHELM2() {
    if (isAnnotationTrue()) {
      return sourceId.getId() + "," + targetId.getId() + "," + sourceUnit + ":"
          + rGroupSource + "-" + targetUnit + ":" + rGroupTarget + "\"" + annotation + "\"";
    } else {
      return sourceId.getId() + "," + targetId.getId() + "," + sourceUnit + ":"
          + rGroupSource + "-" + targetUnit + ":" + rGroupTarget;
    }
  }
public String toHELM2() {
    if (isAnnotationTrue()) {
      return sourceId.getId() + "," + targetId.getId() + "," + sourceUnit + ":"
          + rGroupSource + "-" + targetUnit + ":" + rGroupTarget + "\"" + annotation + "\"";
    } else {
      return sourceId.getId() + "," + targetId.getId() + "," + sourceUnit + ":"
          + rGroupSource + "-" + targetUnit + ":" + rGroupTarget;
    }
  }
method to get a valid HELM2 of the connection notation

@return valid HELM2