Spring Cloud Data Flow fails to create composed tasks that contain $END

[cppwfs]

A composed task definition of timestamp '*'->t1: timestamp 'FOO'->$END does not pass dataflow validation because it says task:$END is not a valid application.
In the DefaultTaskService class where we saveStandardTaskDefinition (Line 110) for a composed task we need to gate it with a if statement like:

if(!composedTaskElementDefinition.getTaskName().contains("$END")) {
	saveStandardTaskDefinition(composedTaskElementDefinition);
}

This way $END is not treated like an app at task definition create time.

[cppwfs]

Refer to issue for additional detail: #4373