code: public ClassSymbol loadClass(Name flatname) throws CompletionFailure {
          boolean absent = classes.get(flatname) == null;
          ClassSymbol c = enterClass(flatname);
          if (c.members_field == null && c.completer != null) {
              try {
                  c.complete();
              } catch (CompletionFailure ex) {
                  if (absent) classes.remove(flatname);
                  throw ex;
              }
          }
          return c;
      }
docs: Load a toplevel class with given fully qualified name
  The class is entered into `classes' only if load was successful.