title: maven: does not download extension written by myself
body: <p>I am not so deep into maven but had to write an extension.
  I successfully deployed and it is present.</p>
  <pre><code>https://www.simuline.eu/RepositoryMaven/eu/simuline/qMngmnt/0.0.3/
  </code></pre>
  <p>Also the version fits.
  But nevertheless, when trying to use,</p>
  <pre><code>Unresolvable build extension: Plugin eu.simuline:qMngmnt:0.0.3 or one of its dependencies could not be resolved: 
  eu.simuline:qMngmnt:jar:0.0.3 was not found in https://repo.maven.apache.org/maven2 during a previous attempt. This failure was cached in the local repository and resolution is not reattempted until the update interval of central has elapsed or updates are forced 
  </code></pre>
  <p>In my pom i have:</p>
  <pre><code> &lt;repositories&gt;
      &lt;repository&gt;
        &lt;id&gt;publicRepoAtSimuline&lt;/id&gt;
        &lt;name&gt;repo at simuline&lt;/name&gt;
        &lt;url&gt;https://www.simuline.eu/RepositoryMaven&lt;/url&gt;
      &lt;/repository&gt;
    &lt;/repositories&gt;
  </code></pre>
  <p>and I use it at the following places:</p>
  <pre><code>&lt;build&gt;
    &lt;extensions&gt;
        &lt;extension&gt;
      &lt;groupId&gt;eu.simuline&lt;/groupId&gt;
      &lt;artifactId&gt;qMngmnt&lt;/artifactId&gt;
      &lt;version&gt;0.0.3&lt;/version&gt;
        &lt;/extension&gt;
  ...
  &lt;plugins&gt;
  ...
      &lt;plugin&gt;
        &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
        &lt;artifactId&gt;maven-checkstyle-plugin&lt;/artifactId&gt;
        &lt;version&gt;3.1.2&lt;/version&gt;
  
        &lt;dependencies&gt;
          &lt;dependency&gt;
            &lt;groupId&gt;com.puppycrawl.tools&lt;/groupId&gt;
            &lt;artifactId&gt;checkstyle&lt;/artifactId&gt;
         &lt;!-- 8.15 has security issue ans seemingly line lengths are wrong --&gt;
               &lt;version&gt;10.1&lt;/version&gt;&lt;!-- TBD: make 8.30, 9.1, 10.1 work --&gt;
          &lt;/dependency&gt;
              &lt;dependency&gt;
            &lt;groupId&gt;eu.simuline&lt;/groupId&gt;
            &lt;artifactId&gt;qMngmnt&lt;/artifactId&gt;
            &lt;version&gt;0.0.3&lt;/version&gt;
              &lt;/dependency&gt;
        &lt;/dependencies&gt;
  ...
  
  &lt;dependencies&gt;
     &lt;dependency&gt;&lt;!-- TBD: clarify: for spotbugs: necessary? --&gt;
        &lt;groupId&gt;eu.simuline&lt;/groupId&gt;
        &lt;artifactId&gt;qMngmnt&lt;/artifactId&gt;
        &lt;version&gt;0.0.3&lt;/version&gt;
        &lt;!--scope&gt;provided&lt;/scope--&gt;
      &lt;/dependency&gt;
  </code></pre>
  <p>Interesting: if i build a new version, <code>qMngmnt-0.0.4-SNAPSHOT</code>
  then of course it is locally installed, and all works fine.
  So I have the impression, download never worked but i did not realize so far.</p>
  <p>What is wrong?</p>
  <p>By the way: I use another artifact as an artifact item
  but neither as a dependency nor as an extension and it works just fine.</p>