@atlaskit/adf-schema/dist/es2019/schema/nodes/unknown-block.js

Shared package that contains the ADF-schema (json) and ProseMirror node/mark specs

const name = 'unknownBlock';
export default {
  group: 'block',
  content: 'inline+',
  marks: '_',
  toDOM() {
    return ['div', {
      'data-node-type': name
    }, 0];
  },
  parseDOM: [{
    tag: `div[data-node-type="${name}"]`
  }]
};