docs: @Override
      protected IIOMetadataNode getStandardTransparencyNode() {
          IIOMetadataNode transparency = new IIOMetadataNode("Transparency");
  
          IIOMetadataNode alpha = new IIOMetadataNode("Alpha");
          transparency.appendChild(alpha);
  
          if (extensions != null) {
              if (extensions.hasAlpha()) {
                  alpha.setAttribute("value", extensions.isAlphaPremultiplied() ? "premultiplied" : "nonpremultiplied");
              }
              else {
                  alpha.setAttribute("value", "none");
              }
          }
          else if (header.getAttributeBits() == 8) {
              alpha.setAttribute("value", "nonpremultiplied");
          }
          else {
              alpha.setAttribute("value", "none");
          }
  
          return transparency;
      }