final void setObject(Iterable<? extends Map.Entry<? extends IN_NAME, ?>> entries) {
        requireNonNull(entries, "entries");
        if (entries == this) {
            return;
        }

        for (Map.Entry<? extends IN_NAME, ?> e : entries) {
            remove(e.getKey());
        }

        if (!addFast(entries)) {
            addObjectSlow(entries);
        }
    }
Invoked when all values are cleared.
core/src/main/java/com/linecorp/armeria/common/StringMultimap.java