title: How a maven dependecy can be defined without version tag?
body: <p>I have a pom which works without defining dependency version in pom works fine and another one without dependency version which does not work. </p>
  
  <p>The one which works:</p>
  
  <pre><code>&lt;project&gt;
      &lt;parent&gt;
          &lt;artifactId&gt;artifact-parent&lt;/artifactId&gt;
          &lt;groupId&gt;group-parent&lt;/groupId&gt;
          &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
      &lt;/parent&gt;
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;group-a&lt;/groupId&gt;
              &lt;artifactId&gt;artifact-a&lt;/artifactId&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;group-a&lt;/groupId&gt;
              &lt;artifactId&gt;artifact-b&lt;/artifactId&gt;
          &lt;/dependency&gt;
      &lt;/dependencies&gt;
  &lt;/project&gt;
  </code></pre>
  
  <p>This one which does not work:</p>
  
  <pre><code>&lt;project&gt;
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;group-a&lt;/groupId&gt;
              &lt;artifactId&gt;artifact-a&lt;/artifactId&gt;
          &lt;/dependency&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;group-a&lt;/groupId&gt;
              &lt;artifactId&gt;artifact-b&lt;/artifactId&gt;
          &lt;/dependency&gt;
      &lt;/dependencies&gt;
  &lt;/project&gt;
  </code></pre>
  
  <p>The only thing differ in these two seems to be:</p>
  
  <pre><code>&lt;parent&gt;
      &lt;artifactId&gt;artifact-parent&lt;/artifactId&gt;
      &lt;groupId&gt;group-parent&lt;/groupId&gt;
      &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
  &lt;/parent&gt;
  </code></pre>
  
  <p>Second one does not work it seems fine to me but my question is why the first one works ?</p>
  
  <p>Quoted from <a href="https://maven.apache.org/pom.html#Dependencies" rel="noreferrer">maven pom reference</a> :</p>
  
  <blockquote>
    <p>This trinity represents the coordinate of a specific project in time,
    demarcating it as a dependency of this project.</p>
  </blockquote>
  
  <p>So my question is how the first one is working?</p>