title: Custom properties in Spring Boot project using Gradle
body: <p>In my Spring Boot project (1.5.6.RELEASE) that I build using gradle, I want to include some custom properties. The approach laid out in the <a href="https://docs.spring.io/spring-boot/docs/current/gradle-plugin/reference/html/" rel="nofollow noreferrer">documentation</a> does not seem to work (on build, I get: <code>Could not set unknown property 'additional' for task ':properties' of type org.gradle.api.tasks.diagnostics.PropertyReportTask.</code>):</p>
  <pre><code>springBoot {
      buildInfo {
          properties {
              additional = [
                  'a': 'alpha',
                  'b': 'bravo'
              ]
          }
      }
  }
  </code></pre>
  <p>Luckily this approach, which I found <a href="https://stackoverflow.com/a/47288548/3368818">here</a>, does work for me (no compile error and I'm then able to access the property from my code):</p>
  <pre><code>springBoot{
      buildInfo {
          additionalProperties = [
              'testpropertykey': 'testpropertyvalue'
          ]
      }
  }
  </code></pre>
  <p>But, since the former is the &quot;officially&quot; documented approach, I would prefer to take that approach. How would I get the former approach to work? I assume I'm missing something - unless the documentation is wrong or maybe this changed from Spring Boot 1.5.6.RELEASE.</p>