public NavigableMap<K, V> toNavigableMap(BinaryOperator<V> mergeFunction) {
        return collect(Collectors.toMap(Entry::getKey, Entry::getValue, mergeFunction, TreeMap::new));
    }
public NavigableMap < K , V > toNavigableMap ( BinaryOperator < V > mergeFunction ) { return collect ( Collectors . toMap ( Entry :: getKey , Entry :: getValue , mergeFunction , TreeMap :: new ) ) ; }
Returns a {@link NavigableMap} containing the elements of this stream.
There are no guarantees on the type or serializability of the
{@code NavigableMap} returned; if more control over the returned
{@code Map} is required, use
{@link #toCustomMap(BinaryOperator, Supplier)}.

<p>
If the mapped keys contains duplicates (according to
{@link Object#equals(Object)}), the value mapping function is applied to
each equal element, and the results are merged using the provided merging
function.

<p>
This is a <a href="package-summary.html#StreamOps">terminal</a>
operation.

<p>
Returned {@code NavigableMap} is guaranteed to be modifiable.

@param mergeFunction a merge function, used to resolve collisions between
values associated with the same key, as supplied to
{@link Map#merge(Object, Object, BiFunction)}
@return a {@code NavigableMap} containing the elements of this stream
@see Collectors#toMap(Function, Function)
@since 0.6.5