[ARCHETYPE-656] Generated archetype changes end of lines to line.separator value

**[David Matějček](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=dmatej)** opened **[ARCHETYPE-656](https://issues.apache.org/jira/browse/ARCHETYPE-656?redirect=false)** and commented

https://github.com/apache/maven-archetype/blob/3a2b725198c3823fd5d7e9f88b665b2e4515a202/archetype-common/src/main/java/org/apache/maven/archetype/generator/DefaultFilesetArchetypeGenerator.java#L741

```java
 writer.write(StringUtils.unifyLineSeparators(stringWriter.toString()));
```

This line manipulates end of line of the source.

That breaks checkstyle rules defined in the common parent of our project where we enforce just '\n'.

It would be good to have it configurable like with encoding. Now is easier to copy-paste another project than to use archetypes.

---

**Affects:** 3.2.1

Start in archetype-common/src/main/java/org/apache/maven/archetype/generator/DefaultFilesetArchetypeGenerator.java around line 741, where generated content is passed through StringUtils.unifyLineSeparators. Compare the requested configurability with the existing encoding configuration. Done means generated files can use a configured line separator without violating the project's enforced '\n' checkstyle rules.

Written by the indexing model from the issue text.