CompletionContributor not work on PsiLiteralExpression

I wanna to auto complete when I am typing on a string literal, but it can't work. I found that the fillCompletionVariants method is not called. What's wrong?

Just like when I type "a", it will show "aaa", "abc" and "abb".

private void action() {
    String[] names = {"aaa", "abc", "abb"};
    String name = "a";
}

@Slf4j
public class MyCompletionContributor extends CompletionContributor {

    public MyCompletionContributor() {
        log.info("MyCompletionContributor");
        extend(CompletionType.BASIC,
                PlatformPatterns.psiElement(PsiLiteralExpression.class).withLanguage(Language.ANY),
                new CompletionProvider<CompletionParameters>() {
                    @Override
                    protected void addCompletions(@NotNull CompletionParameters parameters, @NotNull ProcessingContext context, @NotNull CompletionResultSet result) {
                        log.info("addCompletions: {}, {}", parameters, context);
                        result.addElement(LookupElementBuilder.create("hello"));
                    }
                });
    }

    @Override
    public void fillCompletionVariants(@NotNull CompletionParameters parameters, @NotNull CompletionResultSet result) {
        log.info("fillCompletionVariants: {}, {}", parameters, result);
        super.fillCompletionVariants(parameters, result);
    }
}

<completion.contributor order="first" language="any" implementationClass="org.dependcode.dependcodeplugin.MyCompletionContributor"/>

Can anybody help me? Thanks very much!