[MNG-7052] Do not allow symbols as first character of identifiers in the POM

**[Martin Kanters](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=martinkanters)** opened **[MNG-7052](https://issues.apache.org/jira/browse/MNG-7052?redirect=false)** and commented

In the `DefaultModelValidator` we currently validate identifiers against `a-zA-Z0-9-_.`
Since Maven also allows operators to be used against an identifier, this can result in bugs or at least unexpected behavior for the user.

The minus operator can be used to deactivate a certain profile, so an example would be:
- A project having a profile with the id `-id-of-profile`
- A Maven invocation of `mvn -P-id-of-profile`.

The release of Maven 4 is a nice opportunity to restrict the first character of an id to be `a-zA-Z0-9` . The other characters may still consist of those symbols.

This should apply to all identifiers that we support. The methods that need attention are:
`DefaultModelValidator#validateId` and `DefaultModelValidator#validateIdWithWildcards`.

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**Issue Links:**
- [MNG-7051](https://issues.apache.org/jira/browse/MNG-7051) Optionally skip non-existing profiles
(_**"is caused by"**_)
- [MNG-7051](https://issues.apache.org/jira/browse/MNG-7051) Optionally skip non-existing profiles

- [MNG-7107](https://issues.apache.org/jira/browse/MNG-7107) Relax recently introduced profile id validation

- [MNG-6862](https://issues.apache.org/jira/browse/MNG-6862) Wrong command line analysis for joined profile activation
(_**"is depended upon by"**_)

1 votes, 7 watchers