web/src/main/java/org/springframework/security/web/authentication/preauth/AbstractPreAuthenticatedProcessingFilter.java
@Override
	public void afterPropertiesSet() {
		try {
			super.afterPropertiesSet();
		}
		catch (ServletException e) {
			// convert to RuntimeException for passivity on afterPropertiesSet signature
			throw new RuntimeException(e);
		}
		Assert.notNull(authenticationManager, "An AuthenticationManager must be set");
	}
@Override
	public void afterPropertiesSet() {
		try {
			super.afterPropertiesSet();
		}
		catch (ServletException e) {
			// convert to RuntimeException for passivity on afterPropertiesSet signature
			throw new RuntimeException(e);
		}
		Assert.notNull(authenticationManager, "An AuthenticationManager must be set");
	}
Check whether all required properties have been set.