code: public static Collection<IdentifierExtension> findAll(Collection<? extends Extension> extensions)
      {
          List<IdentifierExtension> result = new ArrayList<IdentifierExtension>();
          for (Extension extension : extensions)
          {
              if (IDENTIFIER_EXTENSION_ID == extension.getId()) result.add((IdentifierExtension)extension);
          }
          return result;
      }
docs: Returns all IdentifierExtensions found in the given collection of extensions.