public static boolean allSubsetsConflict(Collection<BitSet> altsets) {
		return !hasNonConflictingAltSet(altsets);
	}
Determines if every alternative subset in {@code altsets} contains more
than one alternative.

@param altsets a collection of alternative subsets
@return {@code true} if every {@link BitSet} in {@code altsets} has
{@link BitSet#cardinality cardinality} &gt; 1, otherwise {@code false}
runtime/Java/src/org/antlr/v4/runtime/atn/PredictionMode.java