title: Where is the JDK version to be used by Maven compiler specified?
body: <p>When I do not define something as follows in my pom.xml file, where on my system is it defined for Maven which version of Java JDK to use while compiling (I have several versions installed on my system, <code>JAVA_HOME</code> points to one of them)?</p>
  
  <pre><code>&lt;build&gt;
      &lt;plugins&gt;
          &lt;plugin&gt;
              &lt;groupId&gt;org.apache.maven.plugins&lt;/groupId&gt;
              &lt;artifactId&gt;maven-compiler-plugin&lt;/artifactId&gt;
              &lt;version&gt;2.3.2&lt;/version&gt;
              &lt;configuration&gt;
                  &lt;source&gt;1.5&lt;/source&gt;
                  &lt;target&gt;1.5&lt;/target&gt;
              &lt;/configuration&gt;
          &lt;/plugin&gt;
      &lt;/plugins&gt;
  &lt;/build&gt;
  </code></pre>