title: Why does executing "mvn clean package" to build Spark fail with "Some Enforcer rules have failed"?
body: <p>I'm getting build error when trying to build a clean version of latest Spark. I did the following</p>
  
  <p><strong>1)</strong> git clone <a href="https://github.com/apache/spark.git" rel="nofollow">https://github.com/apache/spark.git</a></p>
  
  <p><strong>2)</strong> build <code>mvn -DskipTests clean package</code></p>
  
  <p>But I get the following error:</p>
  
  <blockquote>
    <p>Spark Project Parent POM .......................... FAILURE [2.338s]</p>
    
    <p>...</p>
    
    <p>BUILD FAILURE ...</p>
    
    <p>[ERROR] Failed to execute goal
    org.apache.maven.plugins:maven-enforcer-plugin:1.4:enforce
    (enforce-versions) on project spark-parent_2.10: Some Enforcer rules
    have failed. Look above for specific messages explaining why the rule
    failed. -> [Help 1]</p>
    
    <p>[ERROR]</p>
    
    <p>[ERROR] To see the full stack trace of the errors, re-run Maven with
    the -e switch.</p>
    
    <p>[ERROR] Re-run Maven using the -X switch to enable full debug logging.</p>
    
    <p>[ERROR]</p>
    
    <p>[ERROR] For more information about the errors and possible solutions,
    please read the following articles:</p>
    
    <p>[ERROR] [Help 1]
    <a href="http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException" rel="nofollow">http://cwiki.apache.org/confluence/display/MAVEN/MojoExecutionException</a></p>
  </blockquote>
  
  <p>I'm running Lubuntu 14.04 with the following:</p>
  
  <p>java version "1.7.0_91"</p>
  
  <p>OpenJDK Runtime Environment (IcedTea 2.6.3) (7u91-2.6.3-0ubuntu0.14.04.1)</p>
  
  <p>OpenJDK 64-Bit Server VM (build 24.91-b01, mixed mode)</p>
  
  <p>Apache Maven 3.0.5</p>