code: @Override
      public void readDesign(Element design, DesignContext designContext) {
          super.readDesign(design, designContext);
          Attributes attr = design.attributes();
          if (attr.hasKey("mime-type")) {
              MimeType mimeType = null;
              String mimeTypeString = DesignAttributeHandler.getFormatter().parse(
                       attr.get("mime-type"), String.class);
              try {
                  mimeType = MimeType.valueOfMimeType(mimeTypeString);
              } catch (IllegalArgumentException e) {
                  Logger.getLogger(SignatureField.class.getName()).info(
                          "Unsupported MIME-Type found when reading from design : "
                                  .concat(mimeTypeString));
              }
              setMimeType(mimeType);
          }
      }
docs: /*
  (non-Javadoc)
  
  @see com.vaadin.ui.AbstractComponent#readDesign(org.jsoup.nodes .Element,
  com.vaadin.ui.declarative.DesignContext)