func (s *Server) AddServiceInvocationHandler(method string, fn func(ctx context.Context, in *cc.InvocationEvent) (our *cc.Content, err error)) error {
	if method == "" {
		return fmt.Errorf("servie name required")
	}
	if fn == nil {
		return fmt.Errorf("invocation handler required")
	}
	s.invokeHandlers[method] = fn
	return nil
}
AddServiceInvocationHandler appends provided service invocation handler with its method to the service.
package grpc
import (
	"context"
	"fmt"
	"github.com/golang/protobuf/ptypes/any"
	"github.com/pkg/errors"
	cpb "github.com/dapr/dapr/pkg/proto/common/v1"
	cc "github.com/dapr/go-sdk/service/common"
)