private GetFetcherReply.Builder saveFetcherReply(
            Map.Entry<String, AbstractConfig> fetcherConfig) {
        AbstractFetcher abstractFetcher =
                expiringFetcherStore.getFetchers().get(fetcherConfig.getKey());
        AbstractConfig abstractConfig =
                expiringFetcherStore.getFetcherConfigs().get(fetcherConfig.getKey());
        GetFetcherReply.Builder replyBuilder =
                GetFetcherReply.newBuilder().setFetcherClass(abstractFetcher.getClass().getName())
                        .setFetcherId(abstractFetcher.getName());
        loadParamsIntoReply(abstractConfig, replyBuilder);
        return replyBuilder;
    }
FetcherID is key, The pair is the Fetcher object and the Metadata
tika-grpc/src/main/java/org/apache/tika/pipes/grpc/TikaGrpcServerImpl.java