code: private void validatePathExists(String path, String argumentName) throws FileNotFoundException {
          if (path == null) {
              isValid = false;
              final String msg = String.format("Invalid '%s' argument: null", argumentName);
              throw new FileNotFoundException(msg);
          } else if (!path.contains("*") && !path.contains("?")) {
              File f = new File(path);
              if ("o".equalsIgnoreCase(argumentName.substring(0, 1)) && !"ALL".equalsIgnoreCase(this.getReportFormat())) {
                  final String checkPath = path.toLowerCase();
                  if (checkPath.endsWith(".html") || checkPath.endsWith(".xml") || checkPath.endsWith(".htm")) {
                      if (f.getParentFile() == null) {
                          f = new File(".", path);
                      }
                      if (!f.getParentFile().isDirectory()) {
                          isValid = false;
                          final String msg = String.format("Invalid '%s' argument: '%s'", argumentName, path);
                          throw new FileNotFoundException(msg);
                      }
                  }
              } else if (!f.exists()) {
                  isValid = false;
                  final String msg = String.format("Invalid '%s' argument: '%s'", argumentName, path);
                  throw new FileNotFoundException(msg);
              }
  //        } else if (path.startsWith("//") || path.startsWith("\\\\")) {
  //            isValid = false;
  //            final String msg = String.format("Invalid '%s' argument: '%s'%nUnable to scan paths that start with '//'.", argumentName, path);
  //            throw new FileNotFoundException(msg);
          } else if ((path.endsWith("/*") && !path.endsWith("**/*")) || (path.endsWith("\\*") && path.endsWith("**\\*"))) {
              LOGGER.warn("Possibly incorrect path '{}' from argument '{}' because it ends with a slash star; "
                      + "dependency-check uses ant-style paths", path, argumentName);
          }
      }
docs: Validates whether or not the path points at a file that exists; if the
  path does not point to an existing file a FileNotFoundException is
  thrown.
  
  @param path the paths to validate if they exists
  @param argumentName the argument being validated (e.g. scan, out, etc.)
  @throws FileNotFoundException is thrown if the path being validated does
  not exist.