output: #fixed code
                                  public Result saveLocalTx(Transaction tx) {
          if (tx == null) {
              return Result.getFailed(KernelErrorCode.NULL_PARAMETER);
          }
          byte[] txHashBytes = new byte[0];
          try {
              txHashBytes = tx.getHash().serialize();
          } catch (IOException e) {
              throw new NulsRuntimeException(e);
          }
          CoinData coinData = tx.getCoinData();
  
          if (coinData != null) {
              // delete - from
              List<Coin> froms = coinData.getFrom();
              Set<byte[]> fromsSet = new HashSet<>();
              for (Coin from : froms) {
                  byte[] fromSource = from.getOwner();
                  byte[] utxoFromSource = new byte[tx.getHash().size()];
                  byte[] fromIndex = new byte[fromSource.length - utxoFromSource.length];
                  System.arraycopy(fromSource, 0, utxoFromSource, 0, tx.getHash().size());
                  System.arraycopy(fromSource, tx.getHash().size(), fromIndex, 0, fromIndex.length);
                  Transaction sourceTx = null;
                  try {
                      sourceTx = ledgerService.getTx(NulsDigestData.fromDigestHex(Hex.encode(fromSource)));
                  } catch (Exception e) {
                      throw new NulsRuntimeException(e);
                  }
                  if (sourceTx == null) {
                      return Result.getFailed(AccountLedgerErrorCode.SOURCE_TX_NOT_EXSITS);
                  }
                  byte[] address = sourceTx.getCoinData().getTo().get((int) new VarInt(fromIndex, 0).value).getOwner();
                  fromsSet.add(org.spongycastle.util.Arrays.concatenate(address, from.getOwner()));
              }
              storageService.batchDeleteUTXO(fromsSet);
              // save utxo - to
              List<Coin> tos = coinData.getTo();
              byte[] indexBytes;
              Map<byte[], byte[]> toMap = new HashMap<>();
              for (int i = 0, length = tos.size(); i < length; i++) {
                  try {
                      byte[] outKey = org.spongycastle.util.Arrays.concatenate(tos.get(i).getOwner(), tx.getHash().serialize(), new VarInt(i).encode());
                      toMap.put(outKey, tos.get(i).serialize());
                  } catch (IOException e) {
                      throw new NulsRuntimeException(e);
                  }
              }
              storageService.batchSaveUTXO(toMap);
          }
          return Result.getSuccess();
      }
input: #vulnerable code 
                                  public Result saveLocalTx(Transaction tx) {
          if (tx == null) {
              return Result.getFailed(KernelErrorCode.NULL_PARAMETER);
          }
          byte[] txHashBytes = new byte[0];
          try {
              txHashBytes = tx.getHash().serialize();
          } catch (IOException e) {
              throw new NulsRuntimeException(e);
          }
          CoinData coinData = tx.getCoinData();
  
          if (coinData != null) {
              // delete - from
              List<Coin> froms = coinData.getFrom();
              Set<byte[]> fromsSet = new HashSet<>();
              for (Coin from : froms) {
                  byte[] fromSource = from.getOwner();
                  byte[] utxoFromSource = new byte[tx.getHash().size()];
                  byte[] fromIndex = new byte[fromSource.length - utxoFromSource.length];
                  System.arraycopy(fromSource, 0, utxoFromSource, 0, tx.getHash().size());
                  System.arraycopy(fromSource, tx.getHash().size(), fromIndex, 0, fromIndex.length);
                  Transaction sourceTx = null;
                  try {
                      sourceTx = ledgerService.getTx(NulsDigestData.fromDigestHex(Hex.encode(fromSource)));
                      if (sourceTx == null) {
                          sourceTx = getUnconfirmedTransaction(NulsDigestData.fromDigestHex(Hex.encode(fromSource))).getData();
                      }
                  } catch (Exception e) {
                      throw new NulsRuntimeException(e);
                  }
                  if(sourceTx == null){
                      return Result.getFailed();
                  }
  
                  byte[] address = sourceTx.getCoinData().getTo().get((int) new VarInt(fromIndex, 0).value).getOwner();
                  fromsSet.add(org.spongycastle.util.Arrays.concatenate(address, from.getOwner()));
              }
              storageService.batchDeleteUTXO(fromsSet);
              // save utxo - to
              List<Coin> tos = coinData.getTo();
              byte[] indexBytes;
              Map<byte[], byte[]> toMap = new HashMap<>();
              for (int i = 0, length = tos.size(); i < length; i++) {
                  try {
                      byte[] outKey = org.spongycastle.util.Arrays.concatenate(tos.get(i).getOwner(), tx.getHash().serialize(), new VarInt(i).encode());
                      toMap.put(outKey, tos.get(i).serialize());
                  } catch (IOException e) {
                      throw new NulsRuntimeException(e);
                  }
              }
              storageService.batchSaveUTXO(toMap);
          }
          return Result.getSuccess();
      } 
                              #location 46 
                              #vulnerability type THREAD_SAFETY_VIOLATION