[MARTIFACT-59] artifact plugin should tolerate injected project.build.outputTimestamp

**[Romain Manni-Bucau](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=romain.manni-bucau)** opened **[MARTIFACT-59](https://issues.apache.org/jira/browse/MARTIFACT-59?redirect=false)** and commented

Goal is to not log

```java
Reproducible Build not activated by project.build.outputTimestamp property: see https://maven.apache.org/guides/mini/guide-reproducible-builds.html
```

when the project is actually set but computed from another property and not fail (check mojo) when the setup is the same.

---

**Issue Links:**
- [MARTIFACT-54](https://issues.apache.org/jira/browse/MARTIFACT-54) In multi-module projects check-buildplan fails on project.build.outputTimestamp
(_**"is fixed by"**_)

**Remote Links:**
- [GitHub Pull Request #30
](https://github.com/apache/maven-artifact-plugin/pull/30)

Start by locating the check mojo and reviewing how it handles project.build.outputTimestamp. Compare the behavior with GitHub pull request #30 and MARTIFACT-54. Done means an injected or computed outputTimestamp does not trigger the reproducible-build warning or cause the mojo check to fail.

Written by the indexing model from the issue text.