config/src/main/java/org/springframework/security/config/annotation/web/configurers/AbstractAuthenticationFilterConfigurer.java
public final T defaultSuccessUrl(String defaultSuccessUrl, boolean alwaysUse) {
		SavedRequestAwareAuthenticationSuccessHandler handler = new SavedRequestAwareAuthenticationSuccessHandler();
		handler.setDefaultTargetUrl(defaultSuccessUrl);
		handler.setAlwaysUseDefaultTargetUrl(alwaysUse);
		this.defaultSuccessHandler = handler;
		return successHandler(handler);
	}
public final T defaultSuccessUrl(String defaultSuccessUrl, boolean alwaysUse) {
		SavedRequestAwareAuthenticationSuccessHandler handler = new SavedRequestAwareAuthenticationSuccessHandler();
		handler.setDefaultTargetUrl(defaultSuccessUrl);
		handler.setAlwaysUseDefaultTargetUrl(alwaysUse);
		this.defaultSuccessHandler = handler;
		return successHandler(handler);
	}
Specifies where users will go after authenticating successfully if they have not
visited a secured page prior to authenticating or {@code alwaysUse} is true. This
is a shortcut for calling {@link #successHandler(AuthenticationSuccessHandler)}.

@param defaultSuccessUrl the default success url
@param alwaysUse true if the {@code defaultSuccesUrl} should be used after
authentication despite if a protected page had been previously visited
@return the {@link FormLoginConfigurer} for additional customization