code: @Override
      public void parseContent(StructuralNode parent, List<String> lines) {
          Ruby runtime = JRubyRuntimeContext.get(parent);
          Parser parser = new Parser(runtime, parent, ReaderImpl.createReader(runtime, lines));
  
          StructuralNode nextBlock = parser.nextBlock();
          while (nextBlock != null) {
              parent.append(nextBlock);
              nextBlock = parser.nextBlock();
          }
      }
docs: Parses the given raw asciidoctor content, parses it and appends it as children to the given parent block.
  <p>The following example will add two paragraphs with the role {@code newcontent} to all top
  level sections of a document:
  <pre>
  <verbatim>
  Asciidoctor asciidoctor = ...
  asciidoctor.javaExtensionRegistry().treeprocessor(new Treeprocessor() {
  DocumentRuby process(DocumentRuby document) {
  for (AbstractBlock block: document.getBlocks()) {
  if (block instanceof Section) {
  parseContent(block, Arrays.asList(new String[]{
  "[newcontent]",
  "This is new content"
  "",
  "[newcontent]",
  "This is also new content"}));
  }
  }
  }
  });
  </verbatim>
  </pre>
  
  @param parent The block to which the parsed content should be added as children.
  @param lines  Raw asciidoctor content