Java Utililty Methods List Merge

StringBuilder builder = new StringBuilder();
for (String s : list) {
    builder.append(s);
    builder.append(sep);
return builder.toString();

final StringBuilder sb = new StringBuilder();
for (int i = 0; i < strings.size(); i++) {
    sb.append(strings.get(i));
    if (i < strings.size() - 1) {
        sb.append("\\n");
return sb.toString();
...

return null;

List<Integer> mindexes = new ArrayList<Integer>();
for (int i = 0; i < spans.size() - 1; i++) {
    String s = spans.get(i);
    if (s.length() + indexes.get(i) == indexes.get(i + 1)) {
        mindexes.add(indexes.get(i + 1));
return mindexes;
...

for (Map.Entry<T, List<U>> e : mapToAdd.entrySet()) {
    if (!map.containsKey(e.getKey())) {
        map.put(e.getKey(), new ArrayList<U>());
    map.get(e.getKey()).addAll(e.getValue());

List<T> mergedElements = listOfLists.get(0);
for (int i = 1; i < listOfLists.size(); i++) {
    Collection<? extends T> elements = listOfLists.get(i);
    mergedElements.addAll(elements);
return mergedElements;

if (list == null)
    return "";
StringBuilder sb = new StringBuilder();
for (String item : list) {
    if (item.length() == 0)
        continue;
    if (sb.length() > 0)
        sb.append(seperator); 
...

final List<T> retVal = new ArrayList<T>();
retVal.addAll(a);
retVal.addAll(b);
return retVal;

if (aList == null && bList == null) {
    return Collections.emptyList();
if (aList != null && bList == null) {
    return Collections.unmodifiableList(aList);
if (aList == null && bList != null) {
    return Collections.unmodifiableList(bList);
...

final List<String> v = new ArrayList<String>(Arrays.asList(list));
for (final String anInput : input) {
    if ((null != anInput) && !v.contains(anInput)) {
        v.add(anInput);
return v.toArray(new String[v.size()]);