Core: Use encoding/decoding methods for namespaces and deprecate Splitter/Joiner

[nastra]

We want to eventually make the namespace separator configurable. In order to do that, all the encoding / decoding should go through RestUtil.encodeNamespace and RestUtil.decodeNamespacerather than using the Splitter / Joiner

[nastra]

thanks for the review @Fokko

[mayankvadariya]

This change seem to have affected nested namespace support.

With encoded params, queryParams are further encoded in URIBuilder.

iceberg/core/src/main/java/org/apache/iceberg/rest/HTTPClient.java

Line 230 in 4a3817b

params.forEach(builder::addParameter);

buildUri(path, queryParams) generates following output

before
for queryParams containing parent -> level1�level2
http://localhost:32792/api/catalog/v1/namespaces?parent=level1%1Flevel2&pageToken=

after
for queryParams containing parent -> level1%1Flevel2
http://localhost:32794/api/catalog/v1/namespaces?parent=level1%251Flevel2&pageToken=

@nastra please advise if we need to revert this change.

[nastra]

@mayankvadariya can you please open a separate issue for this? Also do you have a reproducible example where this fails? I'm guessing this is in the Trino PR you linked?

[mayankvadariya]

hi @nastra, I've created #11539 with reproduction steps.