CPS-1812: Merge CM data subscriptions in NCMP when forwarding it to DMI

CPS-1812 - Getting issue details... STATUS

Requirements

#	Interface	Requirement	Additional Information
1	CPS-E-08.e	NCMP is to merge CM Notification Subscriptions Create request for the same CM Handle & XPath(s)	Prevent unnecessary subscription updates to nodes already involved in a subscription to the same path For possible combinations, see table below
2	CPS-E-08.e	Last lights out: only when there is no more subscription for a cm-handle & xpath combination a subscription-delete request wil be send to the relevant DMI
3	CPS-E-08.e	Amalgamation per DMI: all subscription updates originating from a single client request should be send to a single DMI in one request (message). Of course there can be several message if more than 1 DMI is involved.
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#	Error Scenario	Expected behavior	Sign-off
1
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CM Notification Forwarding Check: When forwarding CM Notification NCMP will not check the content to see if the is a valid active subscription. It is assumed that the DMI Plugin as acted on the 'delete subscription' request (that request is NCMPs responsibility). And of course there wil be timing issues it also possible a CM Notification was send just after the subscription-delete was send (from client) but before the whole change had acted upon that.
Retry: NCMP wil only report when actions are pending or rejected. NCMP will not implement a retry mechanism
Wildcards: Wildcards or similar functionality where one string represent 0 or more xpaths is not covered as part of this requirement but it should be kept in mind as a future possibility

#	Assumption	Notes
1	Targets is a collection of xpaths	can be implemented as a json array of strings
2	for the DMI plugin cm-handle-id and xpath are the key to a unique subscription	the client (name) is not relevant for the DMI (should not be included in the request) as this would break the concept of merging!

#	Issue	Notes
1	Is it intended that CM Notification subscription request cover (all) descendants of the given xpath too?!	e.g.. if a child ire removed and there is a subscription for the parent node, will a notification be send (grandchild, child leaf updates etc.) I hope NOT!
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Subscription 1	Subscription 2	DMI Request 1	DMI Request 1
CM-1, [ /p/c1, p/c2 ]	CM-1, [ /p/c1 ]	CM-1, [ /p/c1, p/c2 ]	None
CM-1, [ /p/c1, p/c2 ]	CM-1, [ /p/c1, /p/c2 ]	CM-1, [ /p/c1, p/c2 ]	CM-1, [ /p/c2 ]