[MNGSITE-366] Document priority of --define versus <properties>

**[Elias Elmqvist Wulcan](https://issues.apache.org/jira/secure/ViewProfile.jspa?name=ew)** opened **[MNGSITE-366](https://issues.apache.org/jira/browse/MNGSITE-366?redirect=false)** and commented

I'm pretty sure -D or --define to mvn is supposed to override properties defined in pom.xml under \ but I cannot find this documented anywhere.

Please document this behavior.

I imagine there might be some complexity here regarding inheritence, pom import, profiles and Java's system properties.

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No further details from [MNGSITE-366](https://issues.apache.org/jira/browse/MNGSITE-366?redirect=false)

Start with Maven's --define command-line entry point and pom.xml , then verify how command-line, inherited, imported, profile, and Java system properties interact. Document the confirmed precedence and edge cases in the appropriate Maven site documentation; done means the behavior and its scope are unambiguous.

Written by the indexing model from the issue text.