Gets a {@link BitSet} containing the alternatives in {@code configs}
which are part of one or more conflicting alternative subsets.
@param configs The {@link ATNConfigSet} to analyze.
@return The alternatives in {@code configs} which are part of one or more
conflicting alternative subsets. If {@code configs} does not contain any
conflicting subsets, this method returns an empty {@link BitSet}.
Gets a {@link BitSet} containing the alternatives in {@code configs} which are part of one or more conflicting alternative subsets.
@param configs The {@link ATNConfigSet} to analyze. @return The alternatives in {@code configs} which are part of one or more conflicting alternative subsets. If {@code configs} does not contain any conflicting subsets, this method returns an empty {@link BitSet}.