code: public boolean includeInDocs(final DocumentedFeature documentedFeature, final ClassDoc classDoc, final Class<?> clazz) {
          boolean hidden = !showHiddenFeatures() && clazz.isAnnotationPresent(Hidden.class);
          return !hidden && JVMUtils.isConcrete(clazz);
      }
docs: Determine if a particular class should be included in the output. This is called by the doclet
  to determine if a DocWorkUnit should be created for this feature.
  
  @param documentedFeature feature that is being considered for inclusion in the docs
  @param classDoc for the class that is being considered for inclusion in the docs
  @param clazz class that is being considered for inclusion in the docs
  @return true if the doc should be included, otherwise false