title: NullPointerException when trying build a android application with maven and plugin com.jayway.maven.plugins.android.generation2
body: <p>I am trying building a android application with maven and this pom.xml:</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"&gt;
      &lt;modelVersion&gt;4.0.0&lt;/modelVersion&gt;
      &lt;groupId&gt;org.kleber&lt;/groupId&gt;
      &lt;artifactId&gt;app&lt;/artifactId&gt;
      &lt;version&gt;1.0-SNAPSHOT&lt;/version&gt;
      &lt;packaging&gt;apk&lt;/packaging&gt;
      &lt;name&gt;app&lt;/name&gt;
  
      &lt;properties&gt;
          &lt;project.build.sourceEncoding&gt;UTF-8&lt;/project.build.sourceEncoding&gt;
          &lt;platform.version&gt; 4.1.1.4&lt;/platform.version&gt;
      &lt;/properties&gt;
  
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;com.google.android&lt;/groupId&gt;
              &lt;artifactId&gt;android&lt;/artifactId&gt;
              &lt;version&gt;${platform.version}&lt;/version&gt;
              &lt;scope&gt;provided&lt;/scope&gt;
          &lt;/dependency&gt;
      &lt;/dependencies&gt;
      &lt;build&gt;
          &lt;finalName&gt;${project.artifactId}&lt;/finalName&gt;
          &lt;pluginManagement&gt;
              &lt;plugins&gt;
                  &lt;plugin&gt;
                      &lt;groupId&gt;com.jayway.maven.plugins.android.generation2&lt;/groupId&gt;
                      &lt;artifactId&gt;android-maven-plugin&lt;/artifactId&gt;
                      &lt;version&gt;3.8.2&lt;/version&gt;
                      &lt;extensions&gt;true&lt;/extensions&gt;
                  &lt;/plugin&gt;
              &lt;/plugins&gt;
          &lt;/pluginManagement&gt;
          &lt;plugins&gt;
              &lt;plugin&gt;
                  &lt;groupId&gt;com.jayway.maven.plugins.android.generation2&lt;/groupId&gt;
                  &lt;artifactId&gt;android-maven-plugin&lt;/artifactId&gt;
                  &lt;configuration&gt;
                      &lt;sdk&gt;
                          &lt;platform&gt;16&lt;/platform&gt;
                      &lt;/sdk&gt;
                      &lt;emulator&gt;
                          &lt;avd&gt;avd&lt;/avd&gt;
                      &lt;/emulator&gt;
                  &lt;/configuration&gt;
              &lt;/plugin&gt;
          &lt;/plugins&gt;
      &lt;/build&gt;
  &lt;/project&gt;
  </code></pre>
  
  <p>and keeping getting this error:</p>
  
  <pre><code>[INFO] ------------------------------------------------------------------------
  [INFO] BUILD FAILURE
  [INFO] ------------------------------------------------------------------------
  [INFO] Total time:  1.213 s
  [INFO] Finished at: 2019-09-25T22:03:34-03:00
  [INFO] ------------------------------------------------------------------------
  [ERROR] Failed to execute goal com.jayway.maven.plugins.android.generation2:android-maven-plugin:3.9.0-rc.2:generate-sources (default-generate-sources) on project app: Execution default-generate-sources of goal com.jayway.maven.plugins.android.generation2:android-maven-plugin:3.9.0-rc.2:generate-sources failed.: NullPointerException -&gt; [Help 1]
  [ERROR]
  [ERROR] To see the full stack trace of the errors, re-run Maven with the -e switch.
  [ERROR] Re-run Maven using the -X switch to enable full debug logging.
  [ERROR]
  [ERROR] For more information about the errors and possible solutions, please read the following articles:
  [ERROR] [Help 1] http://cwiki.apache.org/confluence/display/MAVEN/PluginExecutionException
  </code></pre>
  
  <p>Anyone can tell what's the problem here?</p>