title: Maven Surefire only "default-test" run custom executions ignored
body: <p>I am using maven 3.5.4, maven-surefire-plugin 2.19 (I tried maven-surefire-plugin 2.22 also - same result).
  Here's the build section of my POM:</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-surefire-plugin&lt;/artifactId&gt;
              &lt;version&gt;2.19&lt;/version&gt;
              &lt;inherited&gt;true&lt;/inherited&gt;
              &lt;configuration&gt;
                  &lt;parallel&gt;classes&lt;/parallel&gt;
                  &lt;threadCount&gt;20&lt;/threadCount&gt;
              &lt;/configuration&gt;
              &lt;executions&gt;
                  &lt;execution&gt;
                      &lt;id&gt;default-test&lt;/id&gt;
                      &lt;configuration&gt;
                          &lt;excludedGroups&gt;switch-enabled&lt;/excludedGroups&gt;
                      &lt;/configuration&gt;
                  &lt;/execution&gt;
                  &lt;execution&gt;
                      &lt;id&gt;other-tests&lt;/id&gt;
                      &lt;configuration&gt;
                          &lt;groups&gt;switch-enabled&lt;/groups&gt;
                      &lt;/configuration&gt;
                  &lt;/execution&gt;
              &lt;/executions&gt;
          &lt;/plugin&gt;
      &lt;/plugins&gt;
  &lt;/build&gt;
  </code></pre>
  
  <p>I have two sets of unit tests that need to run separately (due to a static boolean variable, thus I set up a TestNG group and have all the tests that need the switch to be on in that group). </p>
  
  <p>Surefire only runs the "default-test" execution and ignore the other execution. I tried the following as well but it also didn't work - no tests were run instead:</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-surefire-plugin&lt;/artifactId&gt;
              &lt;version&gt;2.19&lt;/version&gt;
              &lt;inherited&gt;true&lt;/inherited&gt;
              &lt;configuration&gt;
                  &lt;parallel&gt;classes&lt;/parallel&gt;
                  &lt;threadCount&gt;20&lt;/threadCount&gt;
              &lt;/configuration&gt;
              &lt;executions&gt;
                  &lt;execution&gt;
                      &lt;id&gt;default-test&lt;/id&gt;
                      &lt;configuration&gt;
                          &lt;skip&gt;true&lt;/skip&gt;
                      &lt;/configuration&gt;
                  &lt;/execution&gt;
                  &lt;execution&gt;
                      &lt;id&gt;true-tests&lt;/id&gt;
                      &lt;configuration&gt;
                          &lt;groups&gt;switch-enabled&lt;/groups&gt;
                      &lt;/configuration&gt;
                  &lt;/execution&gt;
                  &lt;execution&gt;
                      &lt;id&gt;false-tests&lt;/id&gt;
                      &lt;configuration&gt;
                          &lt;excludedGroups&gt;switch-enabled&lt;/excludedGroups&gt;
                      &lt;/configuration&gt;
                  &lt;/execution&gt;
              &lt;/executions&gt;
          &lt;/plugin&gt;
      &lt;/plugins&gt;
  &lt;/build&gt;
  </code></pre>
  
  <p>What have I done wrong?</p>