fix(catalog): encode default table locations with UTF-8

[anxkhn]

buildPrefixedLocation in LocalIcebergCatalog derives a table's durable default
storage location by percent-encoding each namespace level and the table name with
URLEncoder.encode(..., Charset.defaultCharset()). Using the JVM's default charset
means that, for a namespace or table whose name contains non-ASCII characters, the
persisted location depends on the platform default charset of whatever JVM created the
table. On a non-UTF-8 JVM the same logical table resolves to a different (or lossy)
location than on a UTF-8 JVM, which breaks portability and the round-trip expectation
that a table's location is stable and deterministic.

This encodes both segments with StandardCharsets.UTF_8. That matches the canonical
namespace codec PolarisEntityUtils.encodeNamespace (which already uses
StandardCharsets.UTF_8) and every other URLEncoder/URLDecoder call site in the
service, so the derived location is now deterministic and charset-independent. These
two call sites were the only ones still using the platform default charset.

Current behavior: with object-storage prefixing enabled
(DEFAULT_LOCATION_OBJECT_STORAGE_PREFIX_ENABLED), the hashed default location for a
table under a non-ASCII namespace/table name is percent-encoded using the JVM default
charset, so it is not stable across deployments with different default charsets.

Expected behavior after this change: the derived location is always the UTF-8
percent-encoded form, independent of the JVM default charset.

Added a regression test (IcebergOverlappingTableTest,
testHashedTableLocationsEncodeNonAsciiIdentifiersAsUtf8) that creates a catalog,
namespace, and table using non-ASCII identifiers with object-storage prefixing enabled
and asserts the derived location ends with the UTF-8 percent-encoded namespace/table
suffix and never contains the raw identifiers. The two small private helper overloads it
uses delegate from the existing helper signatures, so all existing callers are
untouched.

Checklist

• Don't disclose security issues! (contact security@apache.org) - N/A, not a
  security issue.
• Clearly explained why the changes are needed, or linked related issues - see
  above (no matching issue; self-found correctness bug, so no Fixes # line).
• Added/updated tests with good coverage, or manually tested (and explained how) -
  new regression test in IcebergOverlappingTableTest.
• Added comments for complex logic - N/A (one-line encoder change; the test carries
  an explanatory comment).
• Updated CHANGELOG.md - added a ### Fixes entry under [Unreleased].
• Updated documentation in site/content/in-dev/unreleased - N/A (no user-facing
  config/API surface changes; only the encoding of a derived internal path).

Note when actually filling the template on GitHub: check the boxes that apply and
leave the N/A ones per the notes above. Do not paste these parenthetical notes into
the PR verbatim - they are guidance for Anas.

---

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(does not require) disclosing significant AI assistance, and is explicit that the human
submitter is the author and must understand and be able to justify the change end-to-end
in review. This diff is small and the rationale is fully explained above, so a one-line
disclosure is low-cost and honest. Suggested line to append to the PR body if you want
it:

Prepared with AI assistance; I have reviewed the change and take responsibility for it.

Include it or not at your discretion - just be ready to explain the encoding fix and the
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---

Commit

Single commit, Conventional Commits style matching repo history, no DCO sign-off
(correct: ASF uses the ICLA; the history has zero Signed-off-by). Message body already
explains why + what. No Fixes #/Related to # line because there is no matching issue.

fix(catalog): encode default table locations with UTF-8

buildPrefixedLocation derived a table's default storage location by
percent-encoding the namespace levels and table name with
URLEncoder.encode(..., Charset.defaultCharset()). For non-ASCII
identifiers the persisted location then depended on the JVM's default
charset, so the same table could resolve to a different (or lossy)
location on a non-UTF-8 JVM, breaking portability and round-trip
expectations.

Encode both segments with StandardCharsets.UTF_8, matching
PolarisEntityUtils.encodeNamespace and every other URLEncoder call site
in the service. Add a regression test that creates a table under
non-ASCII namespace and table identifiers with object-storage prefixing
enabled and asserts the derived location uses the UTF-8 percent-encoded
form regardless of the platform default charset.

---

Files changed (3)

CHANGELOG.md                                                                    | 1 +
runtime/service/.../catalog/iceberg/LocalIcebergCatalog.java                    | 6 +-  (import swap + 2 encoder args)
runtime/service/src/test/.../catalog/iceberg/IcebergOverlappingTableTest.java   | 69 ++  (new test + 2 helper overloads)

[Copilot]

Pull request overview

This PR makes the derived default table storage location (when object-storage prefixing is enabled) deterministic across JVMs by encoding namespace/table path segments using UTF-8 instead of the platform default charset. This aligns LocalIcebergCatalog with other URL encoding/decoding call sites and the existing namespace codec, and adds a regression test plus a changelog note.

Changes:

• Switch LocalIcebergCatalog.buildPrefixedLocation to URLEncoder.encode(..., StandardCharsets.UTF_8) for namespace levels and table name.
• Add a regression test covering non-ASCII namespace/table identifiers to ensure the stored location uses UTF-8 percent-encoding.
• Document the behavior change in CHANGELOG.md.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
CHANGELOG.md	Notes the switch to UTF-8 percent-encoding for derived default table locations under object-storage prefixing.
runtime/service/src/main/java/org/apache/polaris/service/catalog/iceberg/LocalIcebergCatalog.java	Uses StandardCharsets.UTF_8 for percent-encoding namespace/table segments to make derived locations charset-independent.
runtime/service/src/test/java/org/apache/polaris/service/catalog/iceberg/IcebergOverlappingTableTest.java	Adds a regression test asserting UTF-8 encoding for non-ASCII identifiers and that raw identifiers don’t appear in the durable location.

[dimas-b]

Nice catch 👍 Thanks for your contribution, @anxkhn !

[dimas-b]

This is a good test, but it probably does not belong in the "overlapping table" test class. Why not put it into LocalIcebergCatalogTest?