protected Iterator<WebEnvironment> doLoadWebEnvironmentsFromServiceLoader() {
        ServiceLoader<WebEnvironment> serviceLoader = ServiceLoader.load(WebEnvironment.class);

        return serviceLoader.iterator();
    }
Return the WebEnvironment implementation class to use, either the default
{@link IniWebEnvironment} or a custom class if specified.

@param servletContext current servlet context
@return the WebEnvironment implementation class to use
@see #ENVIRONMENT_CLASS_PARAM
@see IniWebEnvironment
@see #determineWebEnvironment(ServletContext)
@see #getDefaultWebEnvironmentClass(ServletContext)
@deprecated This method is not longer used by Shiro, and will be removed in future versions,
use {@link #determineWebEnvironment(ServletContext)} or {@link #determineWebEnvironment(ServletContext)}
web/src/main/java/org/apache/shiro/web/env/EnvironmentLoader.java