src/main/java/com/wavesplatform/wavesj/Node.java
public String send(Transaction tx) throws IOException {
        return parse(exec(request(tx)), "id").asText();
    }
public String send(Transaction tx) throws IOException {
        return parse(exec(request(tx)), "id").asText();
    }
Sends a signed object and returns its ID.

@param tx signed object (as created by static methods in Transaction class)
@return Transaction ID
@throws IOException