readProjectionFromDocument(doc) {
    for (let n = doc.firstChild; n; n = n.nextSibling) {
      if (n.nodeType == Node.ELEMENT_NODE) {
        return this.readProjectionFromNode(/** @type {Element} */ (n));
      }
    }
    return null;
  }
@param {Document} doc Document.
@return {import("../proj/Projection.js").default} Projection.
@override