public String rawResponse() {
        if (rawResponse == null) {
            rawResponse = composeRawResponse(active, scope, clientId, userName, tokenType,
                                             expiresAt, issuedAt, notBefore,
                                             subject, audience, issuer,
                                             jwtId, extras);
        }
        return rawResponse;
    }
{@code JSON}-formatted raw Token Introspection Response body. If the {@link OAuth2TokenDescriptor} was
not parsed out of the raw response body, this value calculated based on the other
{@link OAuth2TokenDescriptor} values.
oauth2/src/main/java/com/linecorp/armeria/common/auth/oauth2/OAuth2TokenDescriptor.java