Computes the set of conflicting or ambiguous alternatives from a
configuration set, if that information was not already provided by the
parser.
@param reportedAlts The set of conflicting or ambiguous alternatives, as
reported by the parser.
@param configs The conflicting or ambiguous configuration set.
@return Returns {@code reportedAlts} if it is not {@code null}, otherwise
returns the set of alternatives represented in {@code configs}.
Computes the set of conflicting or ambiguous alternatives from a configuration set, if that information was not already provided by the parser.
@param reportedAlts The set of conflicting or ambiguous alternatives, as reported by the parser. @param configs The conflicting or ambiguous configuration set. @return Returns {@code reportedAlts} if it is not {@code null}, otherwise returns the set of alternatives represented in {@code configs}.