output: #fixed code
                                  private static String getAddress() {
          if (LOCAL_ADDRESS != null) {
              return LOCAL_ADDRESS;
          }
          InetAddress localAddress = getFirstValidAddress();
          LOCAL_ADDRESS = localAddress != null ? localAddress.getHostAddress() : null;
          return LOCAL_ADDRESS;
      }
input: #vulnerable code 
                                  private static String getAddress() {
          if (LOCAL_ADDRESS != null) {
              return LOCAL_ADDRESS;
          }
          InetAddress localAddress = getFirstValidAddress();
          LOCAL_ADDRESS = localAddress.getHostAddress();
          return LOCAL_ADDRESS;
      } 
                              #location 6 
                              #vulnerability type NULL_DEREFERENCE