@Override
		public String toString() {
			return "Id{" +
					"containerId='" + containerId + '\'' +
					", unitName='" + unitName + '\'' +
					", moduleType=" + moduleType +
					", moduleLabel='" + moduleLabel + '\'' +
					", index=" + index +
					'}';
		}
Return the "fully qualified" id string for the module instance
this metadata object is tracking. The format for this string is
"deploymentUnitName.type.label.index", for example "ticktock.sink.log.1".

@return fully qualified id string
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/module/store/ModuleMetadata.java