Returns an empty navigable set (immutable). This set is serializable.
<p>This example illustrates the type-safe way to obtain an empty
navigable set:
<pre> {@code
NavigableSet!(string) s = Collections.emptyNavigableSet();
}</pre>
@implNote Implementations of this method need not
create a separate {@code NavigableSet} object for each call.
@param !E type of elements, if there were any, in the set
@return the empty navigable set
Returns an empty navigable set (immutable). This set is serializable.
<p>This example illustrates the type-safe way to obtain an empty navigable set: <pre> {@code NavigableSet!(string) s = Collections.emptyNavigableSet(); }</pre>
@implNote Implementations of this method need not create a separate {@code NavigableSet} object for each call.
@param !E type of elements, if there were any, in the set @return the empty navigable set