[FAB-6070] Add orderer capabilities structures

Certain capabilities may be required of the orderer which are not
required by the rest of the system.  For instance, changing the way a
channel creation request is validated would have an affect on ordering,
but should not have an effect on processing by the peer.  This CR adds
structures to support this.

Change-Id: I4a94a1b8f657f0b56296801672a02717d2162f9a
Signed-off-by: Jason Yellick <jyellick@us.ibm.com>

Author: Jason Yellick

common/capabilities/capabilities_test.go

@@ -24,6 +24,7 @@ func TestSatisfied(t *testing.T) {
 		var capsMap map[string]*cb.Capability
 		for _, provider := range []*registry{
 			NewChannelProvider(capsMap).registry,
+			NewOrdererProvider(capsMap).registry,
 		} {
 			assert.Nil(t, provider.Supported())
 		}
@@ -40,6 +41,7 @@ func TestSatisfied(t *testing.T) {
 		}
 		for _, provider := range []*registry{
 			NewChannelProvider(capsMap).registry,
+			NewOrdererProvider(capsMap).registry,
 		} {
 			assert.Nil(t, provider.Supported())
 		}
@@ -54,6 +56,7 @@ func TestNotSatisfied(t *testing.T) {
 	}
 	for _, provider := range []*registry{
 		NewChannelProvider(capsMap).registry,
+		NewOrdererProvider(capsMap).registry,
 	} {
 		assert.Error(t, provider.Supported())
 	}

common/capabilities/orderer.go

@@ -0,0 +1,41 @@
+/*
+Copyright IBM Corp. All Rights Reserved.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package capabilities
+
+import (
+	cb "github.com/hyperledger/fabric/protos/common"
+)
+
+const (
+	ordererTypeName = "Orderer"
+)
+
+// OrdererProvider provides capabilities information for orderer level config.
+type OrdererProvider struct {
+	*registry
+}
+
+// NewOrdererProvider creates an orderer capabilities provider.
+func NewOrdererProvider(capabilities map[string]*cb.Capability) *OrdererProvider {
+	cp := &OrdererProvider{}
+	cp.registry = newRegistry(cp, capabilities)
+	return cp
+}
+
+// Type returns a descriptive string for logging purposes.
+func (cp *OrdererProvider) Type() string {
+	return ordererTypeName
+}
+
+// HasCapability returns true if the capability is supported by this binary.
+func (cp *OrdererProvider) HasCapability(capability string) bool {
+	switch capability {
+	// Add new capability names here
+	default:
+		return false
+	}
+}