code: protected void importXMLBuilderImpl(BaseXMLBuilder builder) {
          assertElementContainsNoOrWhitespaceOnlyTextNodes(this.xmlNode);
          Node importedNode = getDocument().importNode(
              builder.getDocument().getDocumentElement(), true);
          this.xmlNode.appendChild(importedNode);
      }
docs: Imports another BaseXMLBuilder document into this document at the
  current position. The entire document provided is imported.
  
  @param builder
  the BaseXMLBuilder document to be imported.