You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: server_type_code.go
    path of file: ./repos/goa/grpc/codegen/testdata
    
    the code of the file until where you have to start completion: package testdata

const PayloadWithNestedTypesServerTypeCode = `// NewMethodPayloadWithNestedTypesPayload builds the payload of the
// "MethodPayloadWithNestedTypes" endpoint of the
// "ServicePayloadWithNestedTypes" service from the gRPC request type.
func NewMethodPayloadWithNestedTypesPayload(message *service_payload_with_nested_typespb.MethodPayloadWithNestedTypesRequest) *servicepayloadwith
    
func protobufServicePayloadWithNestedTypespbBParamsToServicepayloadwithnestedtypesBParams(v *service_payload_with_nested_typespb.BParams) *servicepayloadwithnestedtypes.BParams {
	if v == nil {
		return nil
	}
	res := &servicepayloadwithnestedtypes.BParams{}
	if v.B != nil {
		res.B = make(map[string]string, len(v.B))
		for key, val := range v.B {
			tk := key
			tv := val
			res.B[tk] = tv
		}
	}

	return res
}