Rewritten

Co-authored-by: Dorian Burihabwa <75226315+dorian-burihabwa-sonarsource@users.noreply.github.com>

rules/S7465/java/metadata.json

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+{
+  "title": "Unused arguments in lambda expressions should be denoted with an unnamed variable pattern  \"_\"",
+  "type": "CODE_SMELL",
+  "status": "ready",
+  "remediation": {
+    "func": "Constant\/Issue",
+    "constantCost": "2min"
+  },
+  "tags": [
+    "java22"
+  ],
+  "defaultSeverity": "Minor",
+  "ruleSpecification": "RSPEC-7465",
+  "sqKey": "S7465",
+  "scope": "All",
+  "defaultQualityProfiles": ["Sonar way"],
+  "quickfix": "targeted",
+  "code": {
+    "impacts": {
+      "MAINTAINABILITY": "LOW"
+    },
+    "attribute": "CLEAR"
+  }
+}

rules/S7465/java/rule.adoc

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+== Why is this an issue?
+
+Library authors often design versatile APIs to handle diverse scenarios.
+When such an API takes a function as an argument, we may find ourselves
+writing a lambda expression where some arguments are unused.
+Naming these arguments can lead to unnecessary verbosity.
+Java 22 introduces the unnamed variable pattern `_` that clearly indicates
+the intent not to use the variable.
+
+== How to fix it
+In order to clearly indicate the intent, unused arguments should be denoted
+with an unnamed variable pattern `_`.
+
+=== Code examples
+
+==== Noncompliant code example
+[source,java,diff-id=1,diff-type=noncompliant]
+----
+BiFunction<Integer,Integer,Integer> f = (a, unused) -> a; // Noncompliant
+
+// ...
+
+firstValueMap.merge(event.id, event.value, (oldValue, unused) -> oldValue);  // Noncompliant
+----
+
+==== Compliant solution
+[source,java,diff-id=1,diff-type=compliant]
+----
+BiFunction<Integer,Integer,Integer> f2 = (a, _) -> a;
+
+// ...
+
+firstValueMap.merge(event.id, event.value, (oldValue, _) -> oldValue);
+----
+
+== Resources
+=== Documentation
+
+* OpenJDK - https://openjdk.org/jeps/456[JEP 456: Unnamed Variables & Patterns]

rules/S7465/metadata.json

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+{
+}