code: String getDefaultInstanceTopLevelId() {
          String topLevelConfigId = (String) config.get("config.id");
          if (topLevelConfigId != null)
              if (topLevelConfigId.startsWith("com.ibm.ws.jca.resourceAdapter["))
                  return topLevelConfigId.substring(31, topLevelConfigId.length() - 1);
              else if (isEmbedded && topLevelConfigId.startsWith("com.ibm.ws.app.manager["))
                  return topLevelConfigId.substring(23, topLevelConfigId.length() - 1);
          return null;
      }
docs: Returns the id of the top level element under which the properties.* element is nested. Null if not nested.
  
  @return the id of the top level element under which the properties.* element is nested. Null if not nested.