code: public static String resolveWildCardForJarSpec(String workingDirectory, String unresolvedJarSpec,
        Logger log) {
  
      log.debug("resolveWildCardForJarSpec: unresolved jar specification: " + unresolvedJarSpec);
      log.debug("working directory: " + workingDirectory);
  
      if (unresolvedJarSpec == null || unresolvedJarSpec.isEmpty()) {
        return "";
      }
  
      StringBuilder resolvedJarSpec = new StringBuilder();
  
      String[] unresolvedJarSpecList = unresolvedJarSpec.split(",");
      for (String s : unresolvedJarSpecList) {
        // if need resolution
        if (s.endsWith("*")) {
          // remove last 2 characters to get to the folder
          String dirName = String.format("%s/%s", workingDirectory, s.substring(0, s.length() - 2));
  
          File[] jars = null;
          try {
            jars = getFilesInFolderByRegex(new File(dirName), ".*jar");
          } catch (FileNotFoundException fnfe) {
            log.warn("folder does not exist: " + dirName);
            continue;
          }
  
          // if the folder is there, add them to the jar list
          for (File jar : jars) {
            resolvedJarSpec.append(jar.toString()).append(",");
          }
        } else { // no need for resolution
          resolvedJarSpec.append(s).append(",");
        }
      }
  
      log.debug("resolveWildCardForJarSpec: resolvedJarSpec: " + resolvedJarSpec);
  
      // remove the trailing comma
      int lastCharIndex = resolvedJarSpec.length() - 1;
      if (lastCharIndex >= 0 && resolvedJarSpec.charAt(lastCharIndex) == ',') {
        resolvedJarSpec.deleteCharAt(lastCharIndex);
      }
  
      return resolvedJarSpec.toString();
    }
docs: <pre>
  If there's a * specification in the "jar" argument (e.g. jar=./lib/*,./lib2/*),
  this method helps to resolve the * into actual jar names inside the folder, and in order.
  This is due to the requirement that Spark 1.4 doesn't seem to do the resolution for users
  
  </pre>
  
  @return jar file list, comma separated, all .../* expanded into actual jar names in order