src/language-js/embed/graphql.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 potential 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);
}