What does [++]*+ stands for in regexp

What does [++]*+ stands for in regexp

I'm using http://code.google.com/p/libphonenumber/ and I try to check some
phone numbers if they are valid with regexp pattern VALID_PHONE_NUMBER
which can be found here
http://code.google.com/p/libphonenumber/source/browse/trunk/java/libphonenumber/src/com/google/i18n/phonenumbers/PhoneNumberUtil.java
and it looks like this
private static final String VALID_PHONE_NUMBER = DIGITS + "{" +
MIN_LENGTH_FOR_NSN + "}" + "|" + "[" + PLUS_CHARS + "]*+(?:[" +
VALID_PUNCTUATION + STAR_SIGN + HASH_SIGN +"]*" + DIGITS + "){3,}[" +
VALID_PUNCTUATION + STAR_SIGN + HASH_SIGN + VALID_ALPHA + DIGITS + "]*";
On my Android phone this expression is compiled to following
\p{Nd}{1}|[++]*+(?:[-x--?-?--/ ­??
()()[].\[\]/~?~~*#]*\p{Nd}){3,}[-x--?-?--/ ­??
()()[].\[\]/~?~~*#DEFGABCLMNOHIJKUTWVQPSRYXZdefgabclmnohijkutwvqpsryxz\p{Nd}]*



What does it mean
[++]*+
?
Does it mean "plus-or-plus zero-or-more-times and then plus?
Does it make any sense to have two pluses next to each other?