[MRELEASE-1044] Allow JDomModelETL to be reused

**[Nick Cross](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=rnc)** opened **[MRELEASE-1044](https://issues.apache.org/jira/browse/MRELEASE-1044?redirect=false)** and commented

Would it be possible to consider exposing for reuse e.g. by making them protected the fields in org.apache.maven.shared.release.transform.jdom.JDomModelETL

```java
private Document document;

private String intro = null;
private String outtro = null;
```

In my project I would like to improve the roundtrip ability of rewriting POMs and hence I am looking at reusing this code which provides a much better experience.

Ideally if those fields were protected I could subclass it and perform further actions upon the Document and the outtro strings (e.g. adding '<-- Modified by foo -->' ) etc.

Thanks.

---
No further details from [MRELEASE-1044](https://issues.apache.org/jira/browse/MRELEASE-1044?redirect=false)

Start with org.apache.maven.shared.release.transform.jdom.JDomModelETL and inspect the document, intro, and outtro fields named in the issue. Done means a subclass can reuse the class and access those values to perform additional actions while preserving the existing POM roundtrip behavior.

Written by the indexing model from the issue text.