void addElement(@NotNull LookupElement element,
                  @NotNull CompletionSorter sorter,
                  @NotNull PrefixMatcher prefixMatcher,
                  @NotNull LookupElementPresentation presentation);
void addElement(@NotNull LookupElement element,
                  @NotNull CompletionSorter sorter,
                  @NotNull PrefixMatcher prefixMatcher,
                  @NotNull LookupElementPresentation presentation)