public OAuth2TokenDescriptorBuilder audience(String audience) {
        this.audience = requireNonNull(audience, "audience");
        return this;
    }
{@code aud} Token Introspection Response field,
OPTIONAL. Service-specific string identifier or list of string identifiers representing the
intended audience for this token, as defined at
<a href="https://datatracker.ietf.org/doc/rfc7519/">[RFC7519]</a>.
oauth2/src/main/java/com/linecorp/armeria/common/auth/oauth2/OAuth2TokenDescriptorBuilder.java