code: public static Collection<WOrientConf> createFromApplicationConf(Configuration config, String prefix) {
          Configuration orient = config.getConfiguration(prefix);
  
          if(orient == null){
              return Collections.EMPTY_SET;
          }
  
          Set<String> subkeys = new HashSet<>();
  
          for (String key : orient.asMap().keySet()) {
              subkeys.add(key);
          }
  
          Collection<WOrientConf> subconfs = new ArrayList<>(subkeys.size());
  
          for (String subkey : subkeys) {
              subconfs.add(new WOrientConf(subkey, orient.getConfiguration(subkey)));
          }
  
          return subconfs;
      }
docs: Extract all WOrientConf configuration with the given prefix from the parent wisdom configuration.
  If the prefix is <code>"orientdb"</code> and the configuration is: <br/>
  <code>
  orientdb.default.url = "plocal:/home/wisdom/db"
  orientdb.test.url = "plocal:/home/wisdom/test/db"
  </code>
  <p/>
  the sub configuration will be:
  <p/>
  <code>
  [alias:default]
  url = "plocal:/home/wisdom/db"
  [alias:test]
  url = "plocal:/home/wisdom/test/db"
  </code>
  
  @param config The wisdom configuration
  @param prefix The prefix of the wisdom-orientdb configuration.
  @return A Collection of WOrientConf retrieve from the Wisdom configuration file, or an empty set if there is no configuration under the given prefix.