MultiLineCsvParser needed a test for when an empty String is passed in.

MultiLineCsvParser needed a test for when an empty String is passed to parser.parser(string).

The result should en an immediate EOF from the StringReader, which should correspond to a null being returned

Test added:

  @Test
  public void returnNullWhenEmptyPassedIn() {
    assertNull(parser.parse(""));
  }

Test passed.