title: spring-boot-configuration-processor is not working on maven submodule project
body: <p>I have a maven multi module project with one parent and three child modules.
  The application uses spring boot. In one of the child modules, I have the SpringBootApplication:</p>
  
  <pre><code>@SpringBootApplication
  @EnableConfigurationProperties({AppProperties.class})
  public class MainSpringBootApplication {
      public static void main(String[] args) {
          SpringApplication.run(MainSpringBootApplication.class, args);
      }
  }
  </code></pre>
  
  <p>The App Properties are in the same module:</p>
  
  <pre><code>@Data
  @ConfigurationProperties(prefix = "asdf")
  public class AppProperties {
  ...
  }
  </code></pre>
  
  <p>In the pom.xml of that module there is a dependency for the spring-boot-configuration-processor:</p>
  
  <pre><code>&lt;dependency&gt;
    &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
    &lt;artifactId&gt;spring-boot-configuration-processor&lt;/artifactId&gt;
    &lt;optional&gt;true&lt;/optional&gt;
  &lt;/dependency&gt;
  </code></pre>
  
  <p>Now the problem is, when I run mvn install on the parent project, the target/classes/META-INF/spring-configuration-metadata.json
  file within this child module is not created. When I modify the pom of that child module to directly inherit from:</p>
  
  <pre><code>&lt;parent&gt;
      &lt;groupId&gt;org.springframework.boot&lt;/groupId&gt;
      &lt;artifactId&gt;spring-boot-starter-parent&lt;/artifactId&gt;
      &lt;version&gt;1.2.3.RELEASE&lt;/version&gt;
      &lt;relativePath/&gt; &lt;!-- lookup parent from repository --&gt;
  &lt;/parent&gt;
  </code></pre>
  
  <p>and do mvn install directly on the child module, the target/classes/META-INF/spring-configuration-metadata.json file is generated.</p>
  
  <p>Do you have any hints?</p>