You need to include reactor-netty on the classpath. As by default that is the HTTP client used by WebClient.

pom.xml:

<dependency>
    <groupId>io.projectreactor.netty</groupId>
    <artifactId>reactor-netty</artifactId>
</dependency>

More info: https://docs.spring.io/spring/docs/current/spring-framework-reference/web-reactive.html#webflux-client

spring-web-reactive is the former name of the module, that was changed during the Spring Framework 5.0 milestones. As shown by the link you're mentioning, those artifacts were never available on maven central but only on a Spring artifact repository.

If you take a look at the Spring Boot reference documentation, you'll see that spring-boot-starter-webflux is the dependency to add to your application to pick up spring-webflux, which is the module name for the reactive web support in Spring Framework.

Note that because you've got spring-boot-starter-web already in your application, your application will remain a Spring MVC application if you add the webflux starter, as stated in the reference documentation. There's nothing wrong with that, as Spring MVC supports reactive types in the controller signatures in some cases. It all boils down to what you're trying to achieve here.

There is no WebClient registered as bean.

You can simply use it like this:

WebClient.create().get().uri("http://api.icndb.com/jokes/random")
                  .retrieve().bodyToMono(IcndbJoke.class).block();

Or you use it like described in the Spring Boot Reference Manual

@Service
public class MyService {

    private final WebClient webClient;

    public MyService(WebClient.Builder webClientBuilder) {
        this.webClient = webClientBuilder.baseUrl("https://example.org").build();
    }

    public Mono<Details> someRestCall(String name) {
        return this.webClient.get().uri("/{name}/details", name)
                        .retrieve().bodyToMono(Details.class);
    }

}

See: https://docs.spring.io/spring-boot/docs/current/reference/htmlsingle/#io.rest-client.webclient

Tested converting an existing integration test that was using TestRestTemplate into integration test using WebTestClient

package no.mycompany.myapp.user;

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.web.reactive.AutoConfigureWebTestClient;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.web.reactive.server.WebTestClient;

@AutoConfigureWebTestClient
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class LoginControllerTest {

    @Autowired
    WebTestClient webTestClient;
        
    @Test
    public void postLogin_withoutUserCredentials_receiveUnauthorized() {
        webTestClient.post()
                .uri("/login")
                .exchange()
                .expectStatus().isUnauthorized();
    }
}

Added this to POM

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-webflux</artifactId>
        <scope>test</scope>
    </dependency>

The following was already in POM

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>