code: private Set<String> doSearch(String resourceLocation, Pattern pattern) {
          // get opened namespace
          JDBMNamespaceLookup il = openNamespaces.get(resourceLocation);
  
          Set<String> results = new HashSet<String>();
          for (String value : il.getKeySet()) {
              if (pattern.matcher(value).matches()) {
                  results.add(value);
              }
          }
  
          return results;
      }
docs: Do a search on the values in namespace specified by the resource location
  
  @param resourceLocation resource location, e.g.,
  "http://resource.belframework.org/belframework/1.0/ns/chebi-ids.belns" ,
  can not be null
  @param pattern {@link Pattern}, can not be null
  @return {@link Set} of {@link String}s containing values that match