docs: protected ClassDescriptor discoverDescriptor(String className)
      {
          ClassDescriptor result = (ClassDescriptor) descriptorTable.get(className);
          if (result == null)
          {
              Class clazz;
              try
              {
                  clazz = ClassHelper.getClass(className, true);
              }
              catch (ClassNotFoundException e)
              {
                  throw new OJBRuntimeException("Class, " + className + ", could not be found.", e);
              }
              result = discoverDescriptor(clazz);
           }
          return result;
      }