public OAuth2TokenIntrospectionAuthorizer build() {
        // init introspection request
        final OAuth2Endpoint<OAuth2TokenDescriptor> oAuth2Endpoint =
                new OAuth2Endpoint<>(introspectionEndpoint, introspectionEndpointPath,
                                     OAuth2TokenIntrospectionResponseHandler.INSTANCE);
        final TokenIntrospection tokenIntrospection =
                new TokenIntrospection(oAuth2Endpoint, clientAuthenticationSupplier);

        final Cache<String, OAuth2TokenDescriptor> tokenCache =
                Caffeine.from(cacheSpec == null ? DEFAULT_CACHE_SPEC_OBJ : cacheSpec).build();

        return new OAuth2TokenIntrospectionAuthorizer(tokenCache,
                                                      accessTokenType, realm, permittedScope.build(),
                                                      tokenIntrospection);
    }
Builds a new instance of {@link OAuth2TokenIntrospectionAuthorizer} using configured parameters.
oauth2/src/main/java/com/linecorp/armeria/server/auth/oauth2/OAuth2TokenIntrospectionAuthorizerBuilder.java