code: @Override
      public synchronized RuntimeEngine getRuntimeEngine(Context<?> context) {
          Object contextId = context != null ? context.getContextId() : null;
          if (contextId == null) {
              contextId = NULL_CONTEXT_ID;
          }
          RuntimeEngine engine = _engines.get(contextId);
          if (engine == null) {
              engine = new ExtendedRemoteRuntimeEngine(_configuration, context);
              _engines.put(contextId, engine);
          }
          return engine;
      }
docs: {@inheritDoc}