[FAB-10848] Invalid seek type in Event Client

When the Event Client is created using the WithBlockEvents
option, only pass the WithSeekType option to the event
service if seekType has been specified. Also, add a check
for blank seek type in the event service to prevent
against this case.

Change-Id: I48cff39582f34d3c0d40f327555fcba79ab7a4a1
Signed-off-by: Bob Stasyszyn <Bob.Stasyszyn@securekey.com>

pkg/client/event/event.go

@@ -15,6 +15,7 @@ SPDX-License-Identifier: Apache-2.0
 package event
 
 import (
+	"github.com/hyperledger/fabric-sdk-go/pkg/common/options"
 	"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/context"
 	"github.com/hyperledger/fabric-sdk-go/pkg/common/providers/fab"
 	"github.com/hyperledger/fabric-sdk-go/pkg/fab/events/client"
@@ -55,7 +56,15 @@ func New(channelProvider context.ChannelProvider, opts ...ClientOption) (*Client
 
 	var es fab.EventService
 	if eventClient.permitBlockEvents {
-		es, err = channelContext.ChannelService().EventService(client.WithBlockEvents(), deliverclient.WithSeekType(eventClient.seekType), deliverclient.WithBlockNum(eventClient.fromBlock))
+		var opts []options.Opt
+		opts = append(opts, client.WithBlockEvents())
+		if eventClient.seekType != "" {
+			opts = append(opts, deliverclient.WithSeekType(eventClient.seekType))
+			if eventClient.seekType == seek.FromBlock {
+				opts = append(opts, deliverclient.WithBlockNum(eventClient.fromBlock))
+			}
+		}
+		es, err = channelContext.ChannelService().EventService(opts...)
 	} else {
 		es, err = channelContext.ChannelService().EventService()
 	}

pkg/fab/events/deliverclient/opts.go

@@ -74,7 +74,11 @@ func (p *params) SetFromBlock(value uint64) {
 
 func (p *params) SetSeekType(value seek.Type) {
 	logger.Debugf("SeekType: %s", value)
-	p.seekType = value
+	if value != "" {
+		p.seekType = value
+	} else {
+		logger.Warnf("SeekType must not be empty. Defaulting to %s", p.seekType)
+	}
 }
 
 func (p *params) SetResponseTimeout(value time.Duration) {