Update RequestConverters.java

[Kingsea442]

fix exception when _id is like this /a/b/c

code:
UpdateRequest updateRequest = new UpdateRequest("dev_product","product", "/sku/test.com/48923AQ3");
// ignore
restHighLevelClient.update(updateRequest, RequestOptions.DEFAULT);
exception:
[dev_product/6rBlaK6USlaQ5frl4HGmWg][[dev_product][0]] ElasticsearchStatusException[Elasticsearch exception [type=document_missing_exception, reason=[product][test.com/48923AQ3]: document missing]

URI [/dev_product/product/test.com%2F48923AQ3/_update?timeout=1m], status line [HTTP/1.1 404 Not Found]

the exception is convert this id /sku/test.com/48923AQ3 to test.com%2F48923AQ3

[elasticmachine]

Pinging @elastic/es-core-features

[jakelandis]

@Kingsea442 - Can you please add unit tests. Specifically ones that ensure this comment is still valid:

//we prepend "/" to the path part to make this path absolute, otherwise there can be issues with
//paths that start with - or contain :

[javanna]

hi @Kingsea442 ,
your fix is causing some failures in RequestConvertersTests. I do see the problem you are having though and I will look into how we can fix it.

[Kingsea442]

hi @Kingsea442 ,
your fix is causing some failures in RequestConvertersTests. I do see the problem you are having though and I will look into how we can fix it.

great! thanks.

[javanna]

Closing in favour of #37405 which I just opened. I did not have time to work on a fix yet but I have added a failing test to the linked issue, which shows the problem.