default RequestHeadersBuilder acceptLanguages(LanguageRange... acceptedLanguages) {
        return acceptLanguages(ImmutableList.copyOf(
                requireNonNull(acceptedLanguages, "acceptedLanguages")));
    }
Sets the {@code "accept-language"} header.
@param acceptedLanguages the accepted languages.
@return {@code this}
core/src/main/java/com/linecorp/armeria/common/RequestHeadersBuilder.java