WW-5668 Bound the localized-text provider caches and align request-locale resolution

[lukaszlenart]

Fixes WW-5668

Follow-up to WW-5540. Two related, independent changes to the localized-text subsystem.

1. Bounded localized-text caches

AbstractLocalizedTextProvider kept its five internal caches (bundlesMap, messageFormats, missingBundles, and the classHierarchyCache / packageHierarchyCache added in WW-5540) as plain ConcurrentHashMaps with no configurable upper bound or eviction. The rest of the framework already standardises on bounded caches via OgnlCacheFactory (struts.ognl.expressionCacheMaxSize, struts.proxy.cacheMaxSize, both wtlfu); these were the outlier.

• Reuse the existing OgnlCache abstraction (DefaultOgnlCacheFactory) for all five caches, with configurable size and eviction.
• New constants struts.i18n.cacheType (default wtlfu) and struts.i18n.cacheMaxSize (default 10000), documented in default.properties.
• Added remove(key) to OgnlCache (needed by clearBundle).
• Caches are transient and rebuilt in readObject so the provider stays serializable; a dedicated lock replaces synchronizing on the now-reassignable bundlesMap.

All five caches are pure/reconstructible, so eviction can only cause a recompute, never a wrong or stale localized result.

2. Consistent request-locale resolution (opt-in)

I18nInterceptor validates a resolved locale against the available-locale set (LocaleProvider.isValidLocale), but Dispatcher.getLocale(...) (used when struts.locale is unset) returns request.getLocale() directly without that check.

• New struts.locale.validateRequestLocale (default false — current behaviour preserved byte-for-byte). When enabled, Dispatcher resolves request-derived locales against the JVM available-locale set, falling back to the configured struts.locale (else the JVM default), consistent with I18nInterceptor.

Testing

• New tests: cache bound invariant, correctness under eviction, reload clears, serialize→deserialize→findText, cache-type selection, and the three Dispatcher flag states (off / on-available / on-fallback).
• Full core suite green.

Backward compatibility

• Part 1 changes internal cache implementations only; eviction is correctness-safe; defaults match existing cache conventions.
• Part 2 is fully opt-in and defaults off.

🤖 Generated with Claude Code

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
86.8% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[Copilot]

Pull request overview

This PR updates Struts’ localized-text (i18n) subsystem to (1) bound and standardize the internal localized-text provider caches using the existing OgnlCache abstraction, and (2) optionally make request-locale resolution in Dispatcher consistent with I18nInterceptor by validating request-derived locales against the JVM available-locale set.

Changes:

• Replaced five unbounded ConcurrentHashMap-based caches in AbstractLocalizedTextProvider with configurable, bounded OgnlCache instances (struts.i18n.cacheType, struts.i18n.cacheMaxSize) and ensured caches rebuild after deserialization.
• Added an additive remove(K) operation to OgnlCache and implemented it across cache implementations to support existing bundle-clearing behavior.
• Added struts.locale.validateRequestLocale (default false) and routed Dispatcher’s request-locale selection through a helper that can validate/fallback when enabled, plus accompanying tests.

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
docs/superpowers/specs/2026-07-30-WW-5668-i18n-cache-bounds-locale-resolution-design.md	New design spec documenting bounded i18n caches and opt-in request-locale validation behavior.
docs/superpowers/plans/2026-07-30-WW-5668-i18n-cache-bounds-locale-resolution.md	New implementation plan detailing the steps, constants, and tests for the change set.
core/src/main/java/org/apache/struts2/ognl/OgnlCache.java	Adds remove(K) to the cache abstraction to support bundle cache entry removal.
core/src/main/java/org/apache/struts2/ognl/OgnlCaffeineCache.java	Implements remove(K) for the Caffeine-backed cache.
core/src/main/java/org/apache/struts2/ognl/OgnlDefaultCache.java	Implements remove(K) for the default map-backed cache.
core/src/main/java/org/apache/struts2/ognl/OgnlLRUCache.java	Implements remove(K) for the LRU cache.
core/src/test/java/org/apache/struts2/ognl/OgnlCacheRemoveTest.java	New unit test validating remove(K) behavior across cache implementations.
core/src/main/java/org/apache/struts2/StrutsConstants.java	Adds new constants for i18n cache config and request-locale validation flag.
core/src/main/resources/org/apache/struts2/default.properties	Documents new configuration keys and defaults for i18n caches and locale validation.
core/src/main/java/org/apache/struts2/text/AbstractLocalizedTextProvider.java	Converts internal i18n caches to bounded OgnlCache instances; adds rebuild/readObject logic and cache size accessors for tests.
core/src/main/java/org/apache/struts2/text/StrutsLocalizedTextProvider.java	Adds serialVersionUID to align with serialization changes/expectations.
core/src/main/java/org/apache/struts2/text/GlobalLocalizedTextProvider.java	Adds serialVersionUID to align with serialization changes/expectations.
core/src/test/java/org/apache/struts2/text/StrutsLocalizedTextProviderTest.java	Adds tests for cache bounding, eviction correctness, reload clearing, deserialization usability, and cache-type selection.
core/src/main/java/org/apache/struts2/dispatcher/Dispatcher.java	Adds validateRequestLocale flag and resolveRequestLocale() helper; routes getLocale() request-locale retrieval through the helper.
core/src/test/java/org/apache/struts2/dispatcher/DispatcherTest.java	Adds tests for the new request-locale validation flag (off/on/invalid fallback behavior).

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