code: @Override
      public JDocCommentable apply(String nodeName, JsonNode node, JsonNode parent, JDocCommentable generatableType, Schema schema) {
  
          if (node.asBoolean()) {
              generatableType.javadoc().append("\n(Required)");
  
              if (ruleFactory.getGenerationConfig().isIncludeJsr303Annotations()
                      && generatableType instanceof JFieldVar) {
                  ((JFieldVar) generatableType).annotate(NotNull.class);
              }
  
              if (ruleFactory.getGenerationConfig().isIncludeJsr305Annotations()
                      && generatableType instanceof JFieldVar) {
                  ((JFieldVar) generatableType).annotate(Nonnull.class);
              }
          } else {
              if (ruleFactory.getGenerationConfig().isIncludeJsr305Annotations()
                      && generatableType instanceof JFieldVar) {
                  ((JFieldVar) generatableType).annotate(Nullable.class);
              }
          }
  
          return generatableType;
      }
docs: Applies this schema rule to take the required code generation steps.
  <p>
  The required rule simply adds a note to the JavaDoc comment to mark a
  property as required.
  
  @param nodeName
  the name of the schema node for which this "required" rule has
  been added
  @param node
  the "required" node, having a value <code>true</code> or
  <code>false</code>
  @param parent
  the parent node
  @param generatableType
  the class or method which may be marked as "required"
  @return the JavaDoc comment attached to the generatableType, which
  <em>may</em> have an added not to mark this construct as
  required.