web/src/main/java/org/springframework/security/web/context/AbstractSecurityWebApplicationInitializer.java
private String getWebApplicationContextAttribute() {
		String dispatcherServletName = getDispatcherWebApplicationContextSuffix();
		if (dispatcherServletName == null) {
			return null;
		}
		return SERVLET_CONTEXT_PREFIX + dispatcherServletName;
	}
private String getWebApplicationContextAttribute() {
		String dispatcherServletName = getDispatcherWebApplicationContextSuffix();
		if (dispatcherServletName == null) {
			return null;
		}
		return SERVLET_CONTEXT_PREFIX + dispatcherServletName;
	}
Returns the {@link DelegatingFilterProxy#getContextAttribute()} or null if the
parent {@link ApplicationContext} should be used. The default behavior is to use
the parent {@link ApplicationContext}.

<p>
If {@link #getDispatcherWebApplicationContextSuffix()} is non-null the
{@link WebApplicationContext} for the Dispatcher will be used. This means the child
{@link ApplicationContext} is used to look up the springSecurityFilterChain bean.
</p>

@return the {@link DelegatingFilterProxy#getContextAttribute()} or null if the
parent {@link ApplicationContext} should be used