dynamic resource allocation: clean up parameter references

Using APIVersion in the reference leads to ambiguities when the versions
change. Using just APIGroup is better. The examples accidentally used
"apiVersion".

The naming convention (see
https://github.com/kubernetes/community/blob/master/contributors/devel/sig-architecture/api-conventions.md#naming-of-the-reference-field)
is to have Ref as field suffix. In our case that also provides a path
towards (perhaps) at some point inlining parameters because that field then can
be called just "Parameters".

Author: pohly

keps/sig-node/3063-dynamic-resource-allocation/README.md

@@ -419,8 +419,8 @@ kind: ResourceClass
 metadata:
   name: acme-gpu
 driverName: gpu.example.com
-parameters:
-  apiVersion: gpu.example.com/v1
+parametersRef:
+  apiGroup: gpu.example.com
   kind: GPUInit
   name: acme-gpu-init
 ```
@@ -450,8 +450,8 @@ spec:
   - name: "gpu" # this name gets referenced below under "claims"
     template:
       resourceClassName: "acme-gpu"
-      parameters:
-        apiVersion: gpu.example.com/v1
+      parametersRef:
+        apiGroup: gpu.example.com
         kind: GPURequirements
         name: device-consumer-gpu-parameters
   containers:
@@ -1124,13 +1124,13 @@ type ResourceClass struct {
 	// (acme.example.com).
 	DriverName string
 
-	// Parameters references an arbitrary separate object that may hold
+	// ParametersRef references an arbitrary separate object that may hold
 	// parameters that will be used by the
 	// driver when allocating a resource that uses this class. The driver
 	// will be able to distinguish between parameters stored here and and
 	// those stored in ResourceClaimSpec. These parameters here can only be
 	// set by cluster administrators.
-	Parameters ResourceClassParametersReference
+	ParametersRef ResourceClassParametersReference
 
 	// Only nodes matching the selector will be considered by the scheduler
 	// when trying to find a Node that fits a Pod when that Pod uses
@@ -1180,12 +1180,12 @@ type ResourceClaimSpec struct {
 	// reject claims where the class is missing.
 	ResourceClassName string
 
-	// Parameters references a separate object with arbitrary parameters
+	// ParametersRef references a separate object with arbitrary parameters
 	// that will be used by the
 	// driver when allocating a resource for the claim.
 	//
 	// The object must be in the same namespace as the ResourceClaim.
-	Parameters ResourceClaimParametersReference
+	ParametersRef ResourceClaimParametersReference
 
 	// Allocation can start immediately or when a Pod wants to use the
 	// resource. Waiting for a Pod is the default.