public static @NotNull <T> NavigationGutterIconBuilder<T> create(final @NotNull Icon icon,
                                                                   @NotNull NotNullFunction<? super T, ? extends Collection<? extends PsiElement>> converter) {
    return create(icon, converter, null);
  }
public static @NotNull <T> NavigationGutterIconBuilder<T> create(final @NotNull Icon icon,
                                                                   @NotNull NotNullFunction<? super T, ? extends Collection<? extends PsiElement>> converter)