nextSetBit
Returns an index of a next bit which value is true after startIndex (inclusive).
Returns -1 if there is no such bits after startIndex.
Exceptions
IndexOutOfBoundException - if startIndex < 0.
Returns an index of a next bit which value is true after startIndex (inclusive).
Returns -1 if there is no such bits after startIndex.
IndexOutOfBoundException - if startIndex < 0.