#fixed code
                              @Override
  protected boolean onOK(Metadata trailers) {
    ProcessingStatus status = requestManager.onOK();

    if (status == ProcessingStatus.INVALID) {
      // Set an exception.
      onError(INVALID_RESPONSE, trailers);
      return true;
    }

    // There was a problem in the data found in onMessage(), so fail the RPC.
    if (status == ProcessingStatus.SUCCESS || status == ProcessingStatus.NOT_RETRYABLE) {
      // Set the response, with either success, or non-retryable responses.
      completionFuture.set(Arrays.asList(requestManager.buildResponse()));
      return true;
    }

    // Perform a partial retry, if the backoff policy allows it.
    Long nextBackOff = getNextBackoff();
    if (nextBackOff == null) {
      // Return the response as is, and don't retry;
      rpc.getRpcMetrics().markRetriesExhasted();
      completionFuture.set(Arrays.asList(requestManager.buildResponse()));
      operationSpan.addAnnotation("MutationCount", ImmutableMap.of("failureCount",
        AttributeValue.longAttributeValue(requestManager.getRetryRequest().getEntriesCount())));
      return true;
    }

    performRetry(nextBackOff);
    operationSpan.addAnnotation("MutationCount", ImmutableMap.of("retryCount",
      AttributeValue.longAttributeValue(requestManager.getRetryRequest().getEntriesCount())));
    return false;
  }
#vulnerable code 
                              @Override
  protected boolean onOK(Metadata trailers) {
    ProcessingStatus status = requestManager.onOK();

    if (status == ProcessingStatus.INVALID) {
      // Set an exception.
      onError(INVALID_RESPONSE, trailers);
      return true;
    }

    // There was a problem in the data found in onMessage(), so fail the RPC.
    if (status == ProcessingStatus.SUCCESS || status == ProcessingStatus.NOT_RETRYABLE) {
      // Set the response, with either success, or non-retryable responses.
      completionFuture.set(Arrays.asList(requestManager.buildResponse()));
      return true;
    }

    // Perform a partial retry, if the backoff policy allows it.
    long nextBackOff = getNextBackoff();
    if (nextBackOff == BackOff.STOP) {
      // Return the response as is, and don't retry;
      rpc.getRpcMetrics().markRetriesExhasted();
      completionFuture.set(Arrays.asList(requestManager.buildResponse()));
      operationSpan.addAnnotation("MutationCount", ImmutableMap.of("failureCount",
        AttributeValue.longAttributeValue(requestManager.getRetryRequest().getEntriesCount())));
      return true;
    }

    performRetry(nextBackOff);
    operationSpan.addAnnotation("MutationCount", ImmutableMap.of("retryCount",
      AttributeValue.longAttributeValue(requestManager.getRetryRequest().getEntriesCount())));
    return false;
  } 
                            #location 19 
                            #vulnerability type NULL_DEREFERENCE