code: func (req *Request) AddEndorsersQuery(interests ...*discovery.ChaincodeInterest) (*Request, error) {
  	if err := validateInterests(interests...); err != nil {
  		return nil, err
  	}
  	ch := req.lastChannel
  	q := &discovery.Query_CcQuery{
  		CcQuery: &discovery.ChaincodeQuery{
  			Interests: interests,
  		},
  	}
  	req.Queries = append(req.Queries, &discovery.Query{
  		Channel: ch,
  		Query:   q,
  	})
  	var invocationChains []InvocationChain
  	for _, interest := range interests {
  		invocationChains = append(invocationChains, interest.Chaincodes)
  	}
  	req.addChaincodeQueryMapping(invocationChains)
  	req.addQueryMapping(discovery.ChaincodeQueryType, ch)
  	return req, nil
  }
docs: // AddEndorsersQuery adds to the request a query for given chaincodes
  // interests are the chaincode interests that the client wants to query for.
  // All interests for a given channel should be supplied in an aggregated slice