Multiple API cleanup changes

This microversion implements below API cleanups:

1. 400 for unknown param for query param and for request body.

2. Making server representation always consistent among all APIs
   returning the complete server representation.

3. Change the default return value of ``swap`` field from the empty string
   to 0 (integer) in flavor APIs.

4. Return ``servers`` field always in the response of GET
   hypervisors API even there are no servers on hypervisor

Details: https://specs.openstack.org/openstack/nova-specs/specs/train/approved/api-consistency-cleanup.html

Partial-Implements: blueprint api-consistency-cleanup

Change-Id: I9d257a003d315b84b937dcef91f3cb41f3e24b53

nova/api/openstack/api_version_request.py

@@ -188,6 +188,14 @@ REST_API_VERSION_HISTORY = """REST API Version History:
              in request body to ``POST /servers``. Allow users to specify which
              host/node they want their servers to land on and still be
              validated by the scheduler.
+    * 2.75 - Multiple API cleanup listed below:
+             - 400 for unknown param for query param and for request body.
+             - Making server representation always consistent among GET, PUT
+               and Rebuild serevr APIs response.
+             - Change the default return value of swap field from the empty
+               string to 0 (integer) in flavor APIs.
+             - Return ``servers`` field always in the response of GET
+               hypervisors API even there are no servers on hypervisor.
 """
 
 # The minimum and maximum versions of the API supported
@@ -196,7 +204,7 @@ REST_API_VERSION_HISTORY = """REST API Version History:
 # Note(cyeoh): This only applies for the v2.1 API once microversions
 # support is fully merged. It does not affect the V2 API.
 _MIN_API_VERSION = "2.1"
-_MAX_API_VERSION = "2.74"
+_MAX_API_VERSION = "2.75"
 DEFAULT_API_VERSION = _MIN_API_VERSION
 
 # Almost all proxy APIs which are related to network, images and baremetal