Issue with org.springframework.http.HttpHeaders.CONTENT_LENGTH

I was following BAELDUNG download with binary. So I was figuring out,

import static org.springframework.http.HttpHeaders.CONTENT_LENGTH;

It will work with this dependency,

implementation 'org.springframework:spring-webflux:5.1.9.RELEASE'

In the dependencies list, it will not even show the dependency but errors will go away, the problem is that if I run, I will have this error,

An attempt was made to call a method that does not exist. The attempt was made from the following location:

    org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration$WebFluxConfig.configureResourceCaching(WebFluxAutoConfiguration.java:212)

The following method did not exist:

    org.springframework.web.reactive.config.ResourceHandlerRegistration.setUseLastModified(Z)Lorg/springframework/web/reactive/config/ResourceHandlerRegistration;

The calling method's class, org.springframework.boot.autoconfigure.web.reactive.WebFluxAutoConfiguration$WebFluxConfig, was loaded from the following location:

    jar:file:/C:/Users (not exist)

Do I have to download that jar/HttpHeaders manually to work?