static getMetadata() {
      if (this.hasOwnProperty("_metadata")) {
        // eslint-disable-line
        return this._metadata;
      }
      const metadataObjects = [this.metadata];
      let klass = this; // eslint-disable-line
      while (klass !== UI5Element) {
        klass = Object.getPrototypeOf(klass);
        metadataObjects.unshift(klass.metadata);
      }
      const mergedMetadata = (0, _merge.default)({}, ...metadataObjects);
      this._metadata = new _UI5ElementMetadata.default(mergedMetadata);
      return this._metadata;
    }
Returns an instance of UI5ElementMetadata.js representing this UI5 Web Component's full metadata (its and its parents')
Note: not to be confused with the "get metadata()" method, which returns an object for this class's metadata only
@public
@returns {UI5ElementMetadata}