How to get all remote repositories of a maven project hierarchy?

I'm redirecting all maven repository access to an Artifactory with the following ~/.m2/settings.xml:

<?xml version="1.0" encoding="UTF-8"?>
<settings xsi:schemaLocation="http://maven.apache.org/SETTINGS/1.1.0 http://maven.apache.org/xsd/settings-1.1.0.xsd" xmlns="http://maven.apache.org/SETTINGS/1.1.0"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<!-- unclear what version changes -> use 1.1.0 because it's higher -->
  <servers>
    <server>
      <id>central</id>
      <username>admin</username>
    </server>
    <server>
      <id>snapshots</id>
      <username>admin</username>
    </server>
  </servers>
  <mirrors>
    <mirror>
      <id>artifactory</id>
      <name>artifactory</name>
      <mirrorOf>*</mirrorOf>
      <url>https://[hostname]:[port]/artifactory/remote-repos/</url>
    </mirror>
  </mirrors>
  <profiles>
    <profile>
      <id>artifactory</id>
      <repositories>
        <repository>
          <id>central</id>
          <name>remote-repos</name>
          <url>https://[hostname]:[port]/artifactory/remote-repos</url>
          <snapshots>
            <enabled>false</enabled>
            <updatePolicy>interval:25200</updatePolicy>
          </snapshots>
        </repository>
        <repository>
          <id>snapshots</id>
          <name>remote-repos</name>
          <url>https://[hostname]:[port]/artifactory/remote-repos</url>
          <snapshots />
        </repository>
      </repositories>
      <pluginRepositories>
        <pluginRepository>
          <id>central</id>
          <name>remote-repos</name>
          <url>https://[hostname]:[port]/artifactory/remote-repos</url>
          <snapshots>
            <enabled>false</enabled>
            <updatePolicy>interval:25200</updatePolicy>
          </snapshots>
        </pluginRepository>
        <pluginRepository>
          <id>snapshots</id>
          <name>remote-repos</name>
          <url>https://[hostname]:[port]/artifactory/remote-repos</url>
          <snapshots />
        </pluginRepository>
      </pluginRepositories>
    </profile>
  </profiles>
  <activeProfiles>
    <activeProfile>artifactory</activeProfile>
  </activeProfiles>
</settings>

and thus have to add extra remote repositories which are specified by a project (and its child projects) to the Artifactory instance. I currently use

find . -name pom.xml -exec grep -B 5 -C 5 '<repository>' {} +

which isn't very handy in case an URL is a variable and declared elsewhere and it doesn't skip duplicates. It's not the worst thing in the world, but maybe there's an improvement available.

The following doesn't work:

• mvn versions:display-dependency-updates doesn't display remote repositories
• mvn dependency:list-repositories only works until the first dependency can't be fetched if the proxy is enabled so that I have to figure out where to get it from, add the researched remote repository to Artifactory or move ~/.m2/settings.xml aside - less handy than the find command above

The solution should work recursively, i.e. include all repositories in all child projects and childrens child projects, etc.

It makes a lot of sense that a solutions don't require to download the dependencies directly from the remote repository first without the proxy since I'd like to transfer them through the Maven proxy immediately if possible - it's not a requirement, though.