[Misc] Use instanceof pattern matching instead of explicit casts (SonarQube java:S6201)

[claude]

Jira URL

N/A — [Misc] commit, no JIRA issue (SonarQube cleanup).

Changes

Description

• Fixes 73 open SonarCloud java:S6201 issues — "Replace this instanceof check and cast with 'instanceof Foo foo'" — in the crypto modules:
  • xwiki-commons-crypto-common (14)
  • xwiki-commons-crypto-password (31)
  • xwiki-commons-crypto-pkix (14)
  • xwiki-commons-crypto-signer (8)
  • xwiki-commons-crypto-store-filesystem (6)
• Each redundant cast is replaced by the pattern variable bound by the enclosing instanceof check; where an explicit local was declared just to hold the cast, that declaration is removed and the pattern variable takes its name.

Clarifications

• The change is behaviour-neutral: the pattern variable has exactly the static type of the cast it replaces, so overload resolution (e.g. the serializeParameter/getInstance overload sets) is unchanged.
• xwiki-commons-crypto-cipher (4 more sites) was deliberately left out: removing the covered CHECKCAST instructions there takes the module's JaCoCo instruction ratio from 0.70 to 0.69 and fails jacoco:check. Lowering the pinned ratio to go green would be the wrong fix, so those 4 issues are left open for a change that also adds the missing tests.

Screenshots & Video

N/A — no UI change.

Executed Tests

mvn clean install -B -ntp -Plegacy,quality -pl \
  xwiki-commons-core/xwiki-commons-crypto/xwiki-commons-crypto-common,\
  xwiki-commons-core/xwiki-commons-crypto/xwiki-commons-crypto-password,\
  xwiki-commons-core/xwiki-commons-crypto/xwiki-commons-crypto-pkix,\
  xwiki-commons-core/xwiki-commons-crypto/xwiki-commons-crypto-signer,\
  xwiki-commons-core/xwiki-commons-crypto/xwiki-commons-crypto-store/xwiki-commons-crypto-store-filesystem

BUILD SUCCESS — full unit-test suites, Checkstyle, Revapi and the JaCoCo coverage gate all pass.

Expected merging strategy

• Prefers squash: Yes
• Backport on branches:
  • None — cleanup only, no need to backport.

Related

Part of the same SonarQube sweep (one PR per repo, mergeable independently):

• [Misc] Use instanceof pattern matching instead of explicit casts (SonarQube java:S6201) #1854 — 73 java:S6201 fixes in the crypto modules
• [Misc] Use instanceof pattern matching instead of explicit casts (SonarQube java:S6201) xwiki-rendering#391 — 52 java:S6201 fixes across the rendering modules
• [Misc] Use static imports for Mockito methods in unit tests (SonarQube java:S8924) xwiki-platform#6012 — 27 java:S8924 fixes in unit tests

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