feat: Java 21 modernization — retrieve

[devin-ai-integration]

Description of the Change

Conservative Java 21 modernization of the src/gov/nasa/worldwind/retrieve/ package. Changes are limited to internal implementation — no public API, test, or unrelated changes.

Before → After Counts

Pattern	Before	After	Delta
SAM anonymous classes	1	0	−1 (→ lambda)
Traditional instanceof	12	9	−3 (→ pattern matching)
Diamond operator candidates	2	0	−2 (→ <>)

Changes by file

BasicRetrievalService.java (3 modernizations):

• ThreadFactory anonymous inner class → lambda expression (SAM conversion)
• new PriorityBlockingQueue<Runnable>(…) → new PriorityBlockingQueue<>(…) (diamond)
• new ConcurrentLinkedQueue<RetrievalTask>() → new ConcurrentLinkedQueue<>() (diamond)
• e.getCause() instanceof SocketTimeoutException → pattern binding ste, eliminating redundant e.getCause() call
• e.getCause() instanceof SSLHandshakeException → pattern binding sslEx, eliminating redundant e.getCause() calls

URLRetriever.java (1 modernization):

• this.connection instanceof HttpsURLConnection + explicit cast → pattern binding httpsConn

Not converted (conservative rationale)

• 9 remaining instanceof checks have no cast following in the same scope (negated checks, control-flow-only, or cast in a different method). Converting would add unused bindings.
• DiscardPolicy anonymous subclass calls super.rejectedExecution(…) — cannot be a lambda.
• No text blocks, switch expressions, records, or sealed class opportunities in this package.

Why Should This Be In Core?

Keeps the codebase aligned with the Java 21 LTS target established in the foundation branch. These are mechanical, risk-free idiom upgrades to internal implementation.

Benefits

• Reduced boilerplate (lambda replaces 8-line anonymous class)
• Eliminated redundant e.getCause() calls via pattern binding
• Eliminated redundant type arguments via diamond operator
• Verified: JAVA_HOME=jdk-21 ant -f release-build.xml passes (1 pre-existing deprecation warning in CachedDataRaster.java)
• Public API diff: zero signature changes (only line-number shifts)

Potential Drawbacks

None. All changes are internal implementation details with identical runtime behavior.

Applicable Issues

Part of the Java 21 migration effort (child session for retrieve package).

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Build verdict: ✅ PASS — JDK 21, ant -f release-build.xml
Public API diff: ✅ No changes
Session: https://app.devin.ai/sessions/81dc125070134ecba5aa7f0215c99a26
Flags for review: None

Requested by: @jakexcosme

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Devin Review

Status	Commit
⚪ Not started	—

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[devin-ai-integration]

Original prompt from Jake

You are a child Devin session for COG-GTM/WorldWindJava Java 21 migration. Authorized to start. Work ONLY on package retrieve: src/gov/nasa/worldwind/retrieve/. Branch from origin/devin/java21-foundation into devin/java21-retrieve. Target PR base develop. Follow package workflow: pre-count SAM/instanceof, conservative Java 21 modernizations, no public API/test/unrelated changes, JDK21 ant -f release-build.xml, public API diff check, PR title "feat: Java 21 modernization — retrieve", body with before/after counts/rationale/session/verdict/flags. Return structured output.

[devin-ai-integration]

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