title: Maven dependency not in pom.xml
body: <p>I have a project which uses spring. It uses version 3.1.1 but, for some reason I really don't know, some spring artifacts are duplicated with two different versions. I look for the those dependencies in all pom.xml files from my project. I also use the dependecy plugin to figure out where were those dependencies included.</p>
  
  <p>Here you have an extract of the output of <code>mvn dependency:tree</code></p>
  
  <pre><code>[INFO] |  |  \- org.springframework:spring-web:jar:3.1.1.RELEASE:compile
  [INFO] |  |     +- aopalliance:aopalliance:jar:1.0:compile
  [INFO] |  |     +- org.springframework:spring-beans:jar:3.1.1.RELEASE:compile
  [INFO] |  |     +- org.springframework:spring-context:jar:3.1.1.RELEASE:compile
  [INFO] |  |     |  +- org.springframework:spring-aop:jar:3.1.1.RELEASE:compile
  [INFO] |  |     |  +- org.springframework:spring-expression:jar:3.1.1.RELEASE:compile
  [INFO] |  |     |  \- org.springframework:spring-asm:jar:3.0.5.RELEASE:compile
  [INFO] |  |     \- org.springframework:spring-core:jar:3.0.5.RELEASE:compile
  </code></pre>
  
  <p>As far as I know this means that <code>org.springframework:spring-core:jar:3.0.5.RELEASE:compile</code> is included in <code>org.springframework:spring-web:jar:3.1.1.RELEASE:compile</code>.</p>
  
  <p>I workaround this including a dependency with scope <code>provided</code> but I'd need to know why is this happening.</p>
  
  <p><strong>Update</strong>:
  It seems that when I comment the next code the jars are not included in the war.</p>
  
  <pre><code>&lt;dependency&gt;
      &lt;groupId&gt;org.apache.cxf&lt;/groupId&gt;
          &lt;artifactId&gt;cxf-rt-frontend-jaxws&lt;/artifactId&gt;
      &lt;version&gt;${cxf-version}&lt;/version&gt;
  &lt;/dependency&gt;
  ...
  &lt;properties&gt;
      ...
      &lt;cxf-version&gt;2.4.2&lt;/cxf-version&gt;
      &lt;spring.version&gt;3.1.1&lt;/spring.version&gt;
  &lt;/properties&gt;
  </code></pre>