public static boolean allSubsetsEqual(Collection<BitSet> altsets) {
		Iterator<BitSet> it = altsets.iterator();
		BitSet first = it.next();
		while ( it.hasNext() ) {
			BitSet next = it.next();
			if ( !next.equals(first) ) return false;
		}
		return true;
	}
Determines if every alternative subset in {@code altsets} is equivalent.

@param altsets a collection of alternative subsets
@return {@code true} if every member of {@code altsets} is equal to the
others, otherwise {@code false}
runtime/Java/src/org/antlr/v4/runtime/atn/PredictionMode.java