public Set<Map.Entry<K, V>> entrySet() {
        return entrySet0();
    }
Returns a {@link Set} view of the mappings contained in this map. The set
is backed by the map, so changes to the map are reflected in the set, and
vice-versa. If the map is modified while an iteration over the set is in
progress (except through the iterator's own <tt>remove</tt> operation, or
through the <tt>setValue</tt> operation on a map entry returned by the
iterator) the results of the iteration are undefined. The set supports
element removal, which removes the corresponding mapping from the map,
via the <tt>Iterator.remove</tt>, <tt>Set.remove</tt>, <tt>removeAll</tt>
, <tt>retainAll</tt> and <tt>clear</tt> operations. It does not support
the <tt>add</tt> or <tt>addAll</tt> operations.

@return a set view of the mappings contained in this map
src/main/java/com/alibaba/fastjson/util/AntiCollisionHashMap.java