output: #fixed code
                                  public void shutdown() {
          this.isShutDown = true;
          synchronized (this) {
              try {
                  if (uniquePoolEntry != null) // and connection open?
                      uniquePoolEntry.shutdown();
              } catch (IOException iox) {
                  // ignore
                  log.debug("Problem while shutting down manager.", iox);
              } finally {
                  uniquePoolEntry = null;
                  managedConn = null;
              }
          }
      }
input: #vulnerable code 
                                  public void shutdown() {
          this.isShutDown = true;
  
          ConnAdapter conn = managedConn;
          if (conn != null)
              conn.detach();
  
          synchronized (this) {
              try {
                  if (uniquePoolEntry != null) // and connection open?
                      uniquePoolEntry.shutdown();
              } catch (IOException iox) {
                  // ignore
                  log.debug("Problem while shutting down manager.", iox);
              } finally {
                  uniquePoolEntry = null;
                  managedConn = null;
              }
          }
      } 
                              #location 4 
                              #vulnerability type UNSAFE_GUARDED_BY_ACCESS