private @NotNull String assertMessage(float x, float y, int startColumn, int endColumn) {
    return String.join(
      ", ",
      "x: " + x,
      "y: " + y,
      "startColumn: " + startColumn,
      "endColumn: " + endColumn,
      "myCharPositions: " + Arrays.toString(myCharPositions),
      "myCodePoint2Offset: " + Arrays.toString(myCodePoint2Offset)
    );
  }
private @NotNull String assertMessage(float x, float y, int startColumn, int endColumn)