title: Can't use Manifold in gradle java project
body: <p>I have a project based on JDK 11, and I want to use Manifold (<a href="http://manifold.systems/" rel="nofollow noreferrer">http://manifold.systems/</a>) in my java project.</p>
  <p>My build.gradle:</p>
  <pre><code> plugins {
      id 'java'
  }
  //
  
  sourceCompatibility = JavaVersion.VERSION_11
  targetCompatibility = JavaVersion.VERSION_11
  
  repositories {
      maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
  }
  
  dependencies {
      implementation 'org.projectlombok:lombok:1.18.18'
      implementation &quot;io.vavr:vavr:0.10.3&quot;
      implementation 'systems.manifold:manifold-science:2021.1.25'
      compileOnly 'org.projectlombok:lombok:1.18.20'
      annotationProcessor 'org.projectlombok:lombok:1.18.20'
      annotationProcessor group: 'systems.manifold', name: 'manifold-ext', version: '2021.1.25'
      
      testCompileOnly 'org.projectlombok:lombok:1.18.20'
      testAnnotationProcessor 'org.projectlombok:lombok:1.18.20'
      testAnnotationProcessor 'org.openjdk.jmh:jmh-generator-annprocess'
      testImplementation 'org.junit.jupiter:junit-jupiter-engine'
  }
  
  test {
      useJUnitPlatform()
      testLogging {
          events &quot;passed&quot;, &quot;skipped&quot;, &quot;failed&quot;
      }
  }
  </code></pre>
  <p>I tried this:</p>
  <pre><code>import java.math.BigDecimal;
  
  @Extension
  public abstract class ManBigDecimalExt implements ComparableUsing&lt;BigDecimal&gt; {
      /**
       * Supports binary operator {@code +}
       */
      public static BigDecimal plus(@This BigDecimal thiz, BigDecimal that) {
          return thiz.add(that);
      }
  }
  </code></pre>
  <p>But it stated that these Manifold Annotations were not found:</p>
  <pre><code>@Extension
  @This
  </code></pre>
  <p>What should I do?</p>