web/src/main/java/org/springframework/security/web/authentication/AbstractAuthenticationTargetUrlRequestHandler.java
public void setDefaultTargetUrl(String defaultTargetUrl) {
		Assert.isTrue(UrlUtils.isValidRedirectUrl(defaultTargetUrl),
				"defaultTarget must start with '/' or with 'http(s)'");
		this.defaultTargetUrl = defaultTargetUrl;
	}
public void setDefaultTargetUrl(String defaultTargetUrl) {
		Assert.isTrue(UrlUtils.isValidRedirectUrl(defaultTargetUrl),
				"defaultTarget must start with '/' or with 'http(s)'");
		this.defaultTargetUrl = defaultTargetUrl;
	}
public void setDefaultTargetUrl ( String defaultTargetUrl ) { Assert . isTrue ( UrlUtils . isValidRedirectUrl ( defaultTargetUrl ) , "defaultTarget must start with '/' or with 'http(s)'" ) ; this . defaultTargetUrl = defaultTargetUrl ; }
Supplies the default target Url that will be used if no saved request is found in
the session, or the {@code alwaysUseDefaultTargetUrl} property is set to true. If
not set, defaults to {@code /}. It will be treated as relative to the web-app's
context path, and should include the leading <code>/</code>. Alternatively,
inclusion of a scheme name (such as "http://" or "https://") as the prefix will
denote a fully-qualified URL and this is also supported.

@param defaultTargetUrl
Supplies the default target Url that will be used if no saved request is found in the session or the { @code alwaysUseDefaultTargetUrl } property is set to true . If not set defaults to { @code / } . It will be treated as relative to the web - app s context path and should include the leading <code > / < / code > . Alternatively inclusion of a scheme name ( such as http : // or https : // ) as the prefix will denote a fully - qualified URL and this is also supported .