src/language-js/embed.js/printGraphqlComments
function printGraphqlComments(lines) {
  const parts = [];
  let seenComment = false;

  lines.map(textLine => textLine.trim()).forEach((textLine, i, array) => {
    // Lines are either whitespace only, or a comment (with poential whitespace
    // around it). Drop whitespace-only lines.
    if (textLine === "") {
      return;
    }

    if (array[i - 1] === "" && seenComment) {
      // If a non-first comment is preceded by a blank (whitespace only) line,
      // add in a blank line.
      parts.push(concat([hardline, textLine]));
    } else {
      parts.push(textLine);
    }

    seenComment = true;
  });

  // If `lines` was whitespace only, return `null`.
  return parts.length === 0 ? null : join(hardline, parts);
}