output: #fixed code
                                  public void executeCommand(String containerId, String[] command, boolean waitForExecution) {
          String swarmNodeIp = null;
          try {
              List<Task> tasks = dockerClient.listTasks();
              for (Task task : tasks) {
                  ContainerStatus containerStatus = task.status().containerStatus();
                  if (containerStatus != null && containerStatus.containerId().equals(containerId)) {
                      List<Node> nodes = dockerClient.listNodes();
                      for (Node node :nodes) {
                          if (node.id().equals(task.nodeId())) {
                              swarmNodeIp = node.status().addr();
                              execCommandOnRemote(swarmNodeIp, containerId, command);
                          }
                      }
                  }
              }
          } catch (DockerException | InterruptedException | NullPointerException e) {
              logger.debug(nodeId + " Error while executing the command", e);
              ga.trackException(e);
          }
      }
input: #vulnerable code 
                                  public void executeCommand(String containerId, String[] command, boolean waitForExecution) {
          String swarmNodeIp = null;
          try {
              List<Task> tasks = dockerClient.listTasks();
              for (Task task : tasks) {
                  if (task.status().containerStatus().containerId().equals(containerId)) {
                      List<Node> nodes = dockerClient.listNodes();
                      for (Node node :nodes) {
                          if (node.id().equals(task.nodeId())) {
                              swarmNodeIp = node.status().addr();
                          }
                      }
                  }
              }
          } catch (DockerException | InterruptedException | NullPointerException e) {
              logger.debug(nodeId + " Error while executing the command", e);
              ga.trackException(e);
          }
  
          if (swarmNodeIp != null) {
              execCommandOnRemote(swarmNodeIp, containerId, command);
          }
      } 
                              #location 6 
                              #vulnerability type NULL_DEREFERENCE