@Nonnull
    public static List<String> splitAtCommasAndTrim(Iterable<String> input) {
        if(input==null) {
            return Collections.emptyList();
        }
        Iterable<String> nonEmptyInputs = Iterables.filter(input, Predicates.notNull());
        return Lists.newArrayList(Iterables.concat(Iterables.transform(nonEmptyInputs, COMMA_SPLITTER)));
    }
Split each element of an Iterable<String> at commas.
@param input Iterable over strings.
@return An Iterable over string which breaks down each input element at comma boundaries
src/main/java/io/fabric8/maven/docker/util/EnvUtil.java