code: public CompletableFuture<TransactionEvent> sendTransaction(Collection<ProposalResponse> proposalResponses, User userContext) {
  
          return sendTransaction(proposalResponses, getOrderers(), userContext);
  
      }
docs: Send transaction to one of the orderers on the channel using a specific user context.
  
  @param proposalResponses The proposal responses to be sent to the orderer.
  @param userContext       The usercontext used for signing transaction.
  @return a future allowing access to the result of the transaction invocation once complete.