@Override
		protected ContextCloserListener createContextCloserListener(ConfigurableApplicationContext child) {
			return new ModuleContextCloserListener(child, index);
		}
Dedicated sublcass of {@link ParentContextCloserApplicationListener} used to create its own version of
ContextCloserListener that is aware of module order. Special care is taken so that no strong references to the
module context are retained (this is a *static* inner class).

@author Eric Bottard
spring-xd-module/src/main/java/org/springframework/xd/module/core/SimpleModule.java