calloptions.go
func (c *CallOptions) overrideHeaders(headers transportHeaders) {
	if c.Format != "" {
		headers[ArgScheme] = c.Format.String()
	}
	if c.ShardKey != "" {
		headers[ShardKey] = c.ShardKey
	}
	if c.RoutingKey != "" {
		headers[RoutingKey] = c.RoutingKey
	}
	if c.RoutingDelegate != "" {
		headers[RoutingDelegate] = c.RoutingDelegate
	}
	if c.callerName != "" {
		headers[CallerName] = c.callerName
	}
}
func (c *CallOptions) overrideHeaders(headers transportHeaders) {
	if c.Format != "" {
		headers[ArgScheme] = c.Format.String()
	}
	if c.ShardKey != "" {
		headers[ShardKey] = c.ShardKey
	}
	if c.RoutingKey != "" {
		headers[RoutingKey] = c.RoutingKey
	}
	if c.RoutingDelegate != "" {
		headers[RoutingDelegate] = c.RoutingDelegate
	}
	if c.callerName != "" {
		headers[CallerName] = c.callerName
	}
}
// overrideHeaders sets headers if the call options contains non-default values.