protected void getVariantsFromContributors(CompletionParameters parameters,
                                             @Nullable CompletionContributor from,
                                             PrefixMatcher matcher, Consumer<? super CompletionResult> consumer) {
    getVariantsFromContributors(parameters, from, matcher, consumer, null);
  }
protected void getVariantsFromContributors(CompletionParameters parameters,
                                             @Nullable CompletionContributor from,
                                             PrefixMatcher matcher, Consumer<? super CompletionResult> consumer)