Use Kubernetes validation instead of writing logic

[mateusoliveira43]

We currently check for nil NAB backupSpec in code

oadp-non-admin/internal/common/function/function.go

Lines 96 to 98 in 4b2f57f

	if nonAdminBackup.Spec.BackupSpec == nil {
	return nil, fmt.Errorf("BackupSpec is not defined")
	}

instead of using Kubernetes API validation. To achieve this, we just need to remove omitempty here

oadp-non-admin/api/v1alpha1/nonadminbackup_types.go

Line 40 in 4b2f57f

BackupSpec *velerov1api.BackupSpec `json:"backupSpec,omitempty"`