config/src/main/java/org/springframework/security/config/annotation/web/configurers/AbstractAuthenticationFilterConfigurer.java
public T loginProcessingUrl(String loginProcessingUrl) {
		this.loginProcessingUrl = loginProcessingUrl;
		authFilter
				.setRequiresAuthenticationRequestMatcher(createLoginProcessingUrlMatcher(loginProcessingUrl));
		return getSelf();
	}
public T loginProcessingUrl(String loginProcessingUrl) {
		this.loginProcessingUrl = loginProcessingUrl;
		authFilter
				.setRequiresAuthenticationRequestMatcher(createLoginProcessingUrlMatcher(loginProcessingUrl));
		return getSelf();
	}
Specifies the URL to validate the credentials.

@param loginProcessingUrl the URL to validate username and password
@return the {@link FormLoginConfigurer} for additional customization