docs: @Override
      protected IIOMetadataNode getStandardTransparencyNode() {
          IIOMetadataNode transparency = new IIOMetadataNode("Transparency");
  
          IIOMetadataNode alpha = new IIOMetadataNode("Alpha");
          alpha.setAttribute("value", header.getTransparency() == Transparency.OPAQUE ? "none" : "nonpremultiplied");
          transparency.appendChild(alpha);
  
          return transparency;
      }