private String set(ChaincodeStub stub, List<String> args) {
        if (args.size() != 2) {
            throw new RuntimeException("Incorrect arguments. Expecting a key and a value");
        }
        stub.putStringState(args.get(0), args.get(1));
        return args.get(1);
    }
private String set ( ChaincodeStub stub , List < String > args ) { if ( args . size ( ) != 2 ) { throw new RuntimeException ( "Incorrect arguments. Expecting a key and a value" ) ; } stub . putStringState ( args . get ( 0 ) , args . get ( 1 ) ) ; return args . get ( 1 ) ; }
set stores the asset (both key and value) on the ledger. If the key exists,
it will override the value with the new one

@param stub {@link ChaincodeStub} to operate proposal and ledger
@param args key and value
@return value