Exclude ReturnEmptyCollectionRatherThanNull from core-unittests PMD rules

[shai-almog]

Motivation

• Exclude the ReturnEmptyCollectionRatherThanNull PMD rule for the core unit tests to avoid spurious findings from test code.

Description

• Add an <exclude name="ReturnEmptyCollectionRatherThanNull"/> entry to maven/core-unittests/pmd.xml alongside the existing UselessParentheses exclusion.

Testing

• No automated tests were run because this is a configuration-only change.

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Codex Task

[github-actions]

✅ Continuous Quality Report

Test & Coverage

• ✅ Tests: 2282 total, 0 failed, 0 skipped
• 📊 Line coverage: 52.86% [HTML preview] [Download]
  • Lowest covered classes
    • com.codename1.io.rest.RequestBuilder$FetchAsPropertyListActionListener – 0.00%
    • com.codename1.io.rest.RequestBuilder$FetchAsPropertiesActionListener – 0.00%
    • com.codename1.ui.Display$EdtException – 0.00%
    • com.codename1.ui.BrowserWindow$BrowserForm – 0.00%
    • com.codename1.ui.plaf.CSSBorder$LinearGradient – 0.00%
    • com.codename1.io.rest.RequestBuilder$GetAsStringAsyncImplActionListener – 0.00%
    • com.codename1.io.rest.RequestBuilder$GetAsJsonMapActionListener – 0.00%
    • com.codename1.payment.Purchase$SynchronizeReceiptsSyncRunnable – 0.00%
    • com.codename1.io.rest.RequestBuilder$GetAsBytesAsyncImplActionListener – 0.00%
    • com.codename1.io.rest.RequestBuilder$FetchAsJsonMapActionListener – 0.00%

Static Analysis

• ✅ SpotBugs: 0 findings (no issues) [Report archive]
• ❌ PMD: 6177 findings (P2: 42, P3: 5833, P4: 302) [HTML preview] [Download]
  • Top findings
    • P2: CodenameOne/src/com/codename1/capture/Capture.java:250 – Use of modifier volatile is not recommended. (rule: AvoidUsingVolatile)
    • P2: CodenameOne/src/com/codename1/compat/java/util/Objects.java:47 – The method name and parameter number are suspiciously close to equals(Object) (rule: SuspiciousEqualsMethodName)
    • P2: CodenameOne/src/com/codename1/components/StorageImageAsync.java:42 – Use of modifier volatile is not recommended. (rule: AvoidUsingVolatile)
    • P2: CodenameOne/src/com/codename1/components/StorageImageAsync.java:44 – Use of modifier volatile is not recommended. (rule: AvoidUsingVolatile)
    • P2: CodenameOne/src/com/codename1/io/BufferedInputStream.java:38 – Use of modifier volatile is not recommended. (rule: AvoidUsingVolatile)
    • …and 6172 more
• ❌ Checkstyle: 220771 findings (Warning: 220771) [HTML preview] [Download]
  • Top findings
    • Warning: CodenameOne/src/com/codename1/db/ThreadSafeDatabase.java:30:1 – Extra separation in import group before 'java.io.IOException' (rule: CustomImportOrderCheck)
    • Warning: CodenameOne/src/com/codename1/db/ThreadSafeDatabase.java:32 – First sentence of Javadoc is missing an ending period. (rule: SummaryJavadocCheck)
    • Warning: CodenameOne/src/com/codename1/db/ThreadSafeDatabase.java:36 – Line is longer than 100 characters (found 143). (rule: LineLengthCheck)
    • Warning: CodenameOne/src/com/codename1/db/ThreadSafeDatabase.java:39:5 – 'member def modifier' has incorrect indentation level 4, expected level should be 2. (rule: IndentationCheck)
    • Warning: CodenameOne/src/com/codename1/db/ThreadSafeDatabase.java:40:5 – 'member def modifier' has incorrect indentation level 4, expected level should be 2. (rule: IndentationCheck)
    • …and 220766 more

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