Method stringify

github-actions/browserstack/set-browserstack-env.js:19628–19630

* Returns the current summary buffer as a string * * @returns {string} string of summary buffer

()

        let first = true;
        for (const key in this.properties) {
          if (this.properties.hasOwnProperty(key)) {
            const val = this.properties[key];
            if (val) {
              if (first) {
                first = false;
              } else {