title: Missing content in XML coverage report when merging multiple JaCoCo.exec files into 1 file
body: <p>While I have successfully managed to have a unique <code>.exec</code> file generated within the build of my multi-module Java project, I have found that the side-effect of it is that the <code>/target/site/jacoco-aggregate/</code> folder now shows 0% of coverage for all my projects even though the generated <code>mergedJaCoCoReport.exec</code> file contains all the proper coverage information.</p>
  <p>I actually still need the <code>xml</code> report files as <code>SonarCloud</code> can't read the <code>*.exec</code> files.</p>
  <p>If I remove the action below (this action in the end merges all the files into 1 <code>.exec</code> file) from my <code>pom.xml</code>, then the XML report files are valid again</p>
  <pre><code>&lt;configuration&gt; 
                    &lt;destFile&gt;${session.executionRootDirectory}/mergedJaCoCoReport.exec&lt;/destFile&gt; 
                    &lt;append&gt;true&lt;/append&gt; 
              &lt;/configuration&gt; 
  </code></pre>
  <p>Does anyone know if I am missing something here ?
  Thanks in advance</p>
  <p><a href="https://i.stack.imgur.com/In4Jf.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/In4Jf.png" alt="enter image description here" /></a></p>
  <pre><code> &lt;plugin&gt;
           &lt;artifactId&gt;jacoco-maven-plugin&lt;/artifactId&gt;          &lt;groupId&gt;org.jacoco&lt;/groupId&gt;
                                                                 &lt;version&gt;0.8.8&lt;/version&gt;
           &lt;executions&gt;
              &lt;execution&gt;
                 &lt;goals&gt;
                    &lt;goal&gt;prepare-agent&lt;/goal&gt;
                 &lt;/goals&gt;
             &lt;configuration&gt; 
                    &lt;destFile&gt;${session.executionRootDirectory}/mergedJaCoCoReport.exec&lt;/destFile&gt; 
                    &lt;append&gt;true&lt;/append&gt; 
              &lt;/configuration&gt; 
              &lt;/execution&gt;
              &lt;execution&gt;
                 &lt;id&gt;all-tests-report&lt;/id&gt;
                 &lt;phase&gt;verify&lt;/phase&gt;
                 &lt;goals&gt;
                    &lt;goal&gt;report-aggregate&lt;/goal&gt;
                 &lt;/goals&gt;
                 &lt;configuration&gt;
                    &lt;skip&gt;false&lt;/skip&gt;
                 &lt;/configuration&gt;
              &lt;/execution&gt;
              &lt;execution&gt;
                 &lt;id&gt;unit-tests-report&lt;/id&gt;
                 &lt;phase&gt;test&lt;/phase&gt;
                 &lt;goals&gt;
                    &lt;goal&gt;report&lt;/goal&gt;
                 &lt;/goals&gt;
                 &lt;configuration&gt;
                    &lt;skip&gt;false&lt;/skip&gt;
                 &lt;/configuration&gt;
              &lt;/execution&gt;
           &lt;/executions&gt;
        &lt;/plugin&gt;
  </code></pre>