在查看 Flink 示例后，我能够解决它此处 和 Elasticsearch 文档 这里.

I was able to work it out after looking at the Flink example here and the Elasticsearch documentation here.

原来是我在上面设置了错误的配置:

It turned out that I was trying to set the wrong configuration above:

restClientBuilder.setDefaultHeaders(...);

这不是实际需要的设置:

Is not what actually needed setting it is:

restClientBuilder.setHttpClientConfigCallback(...);

一旦您使用了正确的自定义配置，剩下的就非常简单了.所以我缺少的部分是:

Once you use the correct custom configuration the rest is pretty simple. So that part I was missing was:

// provide a RestClientFactory for custom configuration on the internally created REST client
esSinkBuilder.setRestClientFactory(
    restClientBuilder -> {
        restClientBuilder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {

                // elasticsearch username and password
                CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
                credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("$USERNAME", "$PASSWORD"));

                return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
        });
    }
);

最后是 Elasticsearch Sink 的完整片段:

And to finish off here is a full snippet for Elasticsearch Sink:

/*
    Elasticsearch Configuration
*/
List<HttpHost> httpHosts = new ArrayList<>();
httpHosts.add(new HttpHost("127.0.0.1", 9200, "http"));

// use a ElasticsearchSink.Builder to create an ElasticsearchSink
ElasticsearchSink.Builder<ObjectNode> esSinkBuilder = new ElasticsearchSink.Builder<>(
        httpHosts,
        new ElasticsearchSinkFunction<ObjectNode>() {
            private IndexRequest createIndexRequest(ObjectNode payload) {

                // remove the value node so the fields are at the base of the json payload
                JsonNode jsonOutput = payload.get("value");

                return Requests.indexRequest()
                        .index("raw-payload")
                        .type("payload")
                        .source(jsonOutput.toString(), XContentType.JSON);
            }

            @Override
            public void process(ObjectNode payload, RuntimeContext ctx, RequestIndexer indexer) {
                indexer.add(createIndexRequest(payload));
            }
        }
);

// set number of events to be seen before writing to Elasticsearch
esSinkBuilder.setBulkFlushMaxActions(1);

// provide a RestClientFactory for custom configuration on the internally created REST client
esSinkBuilder.setRestClientFactory(
    restClientBuilder -> {
        restClientBuilder.setHttpClientConfigCallback(new RestClientBuilder.HttpClientConfigCallback() {
            @Override
            public HttpAsyncClientBuilder customizeHttpClient(HttpAsyncClientBuilder httpClientBuilder) {

                // elasticsearch username and password
                CredentialsProvider credentialsProvider = new BasicCredentialsProvider();
                credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials("$USERNAME", "$PASSWORD"));

                return httpClientBuilder.setDefaultCredentialsProvider(credentialsProvider);
            }
        });
    }
);

// finally, build and add the sink to the job's pipeline
stream.addSink(esSinkBuilder.build());

我希望这能帮助那些被困在同一个地方的人！

I hope this helps anyone else who was stuck in the same place!