title: Add local external jar - should not point at files within the project directory
body: <p>In my maven project I use custom external <code>my-custom-external</code> jar like this:</p>
  
  <p>pom.xml</p>
  
  <pre><code>&lt;dependencies&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;com.myproject&lt;/groupId&gt;
          &lt;artifactId&gt;my-custom-external&lt;/artifactId&gt;
          &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
          &lt;scope&gt;system&lt;/scope&gt;
          &lt;systemPath&gt;${project.basedir}/libs/my-custom-external-1.0-SNAPSHOT.jar&lt;/systemPath&gt;
      &lt;/dependency&gt;
      &lt;dependency&gt;
          &lt;groupId&gt;org.jetbrains.kotlin&lt;/groupId&gt;
          &lt;artifactId&gt;kotlin-stdlib-jdk8&lt;/artifactId&gt;
          &lt;version&gt;${kotlin.version}&lt;/version&gt;
      &lt;/dependency&gt;
  </code></pre>
  
  <p>I success build project my <code>mvn verify</code> but in console I has warning:</p>
  
  <pre><code>[INFO] Scanning for projects...
  [WARNING] 
  [WARNING] Some problems were encountered while building the effective model for com.myproject:prj_1:jar:1.0-SNAPSHOT
  [WARNING] 'dependencies.dependency.systemPath' for com.myproject:my-custom-extneral:jar should not point at files within the project directory, ${project.basedir}/libs/my-custom-extneral-1.0-SNAPSHOT.jar will be unresolvable by dependent projects @ line 62, column 25
  [WARNING] 
  [WARNING] It is highly recommended to fix these problems because they threaten the stability of your build.
  [WARNING] 
  [WARNING] For this reason, future Maven versions might no longer support building such malformed projects.
  [WARNING] 
  </code></pre>