Where is the parameter in this spring bean comming from

I am new to Spring and need to use the circuit breaker pattern, so I looked at the Spring Cloud Circuit Breaker project and saw this code

@Bean
public Customizer<Resilience4JCircuitBreakerFactory> defaultCustomizer() {
    return factory -> factory.configureDefault(id -> new Resilience4JConfigBuilder(id)
        .timeLimiterConfig(TimeLimiterConfig.custom().timeoutDuration(Duration.ofSeconds(4)).build())
        .circuitBreakerConfig(CircuitBreakerConfig.ofDefaults())
        .build());
 }

where is the factory coming from? is it injected?

The project where this code came from is here demo

cheers,

es

Answer

There is nothing injected.

The methods return a new instance of Customizer<Resilience4JCircuitBreakerFactory>

The code could also be written like this:

@Bean
public Customizer<Resilience4JCircuitBreakerFactory> defaultCustomizer() {
        return new Customizer<Resilience4JCircuitBreakerFactory>() {
            @Override
            public void customize(Resilience4JCircuitBreakerFactory factory) {
                factory.configureDefault(id -> new Resilience4JConfigBuilder(id)
                        .timeLimiterConfig(TimeLimiterConfig.custom().timeoutDuration(Duration.ofSeconds(3)).build())
                        .circuitBreakerConfig(CircuitBreakerConfig.ofDefaults())
                        .build());
            }
        };
    }

But because Customizer is a functional interface it can be written in a lambda.