fix flag include problem

cmd/controller-manager/app/controller-manager.go

@@ -17,6 +17,7 @@ limitations under the License.
 package app
 
 import (
+	"flag"
 	"fmt"
 	"os"
 
@@ -29,6 +30,7 @@ import (
 	extv1b1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1beta1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	utilflag "k8s.io/apiserver/pkg/util/flag"
 	"k8s.io/apiserver/pkg/util/logs"
 
 	"github.com/kubernetes-sigs/federation-v2/cmd/controller-manager/app/options"
@@ -67,6 +69,9 @@ member clusters and does the necessary reconciliation`,
 		},
 	}
 
+	// Add the command line flags from other dependencies(glog, kubebuilder, etc.)
+	cmd.Flags().AddGoFlagSet(flag.CommandLine)
+
 	opts.AddFlags(cmd.Flags())
 	cmd.Flags().BoolVar(&verFlag, "version", false, "Prints the Version info of controller-manager")