[java] Fix pmd#5067: CloseResource: False positive for FileSystems.ge…

…tDefault() (pmd#5225)

Merge pull request pmd#5225 from lukasgraef:issue5067

docs/pages/release_notes.md

@@ -32,11 +32,14 @@ The old rule names still work but are deprecated.
 ### 🐛 Fixed Issues
 * java
   * [#4532](https://github.com/pmd/pmd/issues/4532): \[java] Rule misnomer for JUnit* rules
+* java-errorprone
+  * [#5067](https://github.com/pmd/pmd/issues/5067): \[java] CloseResource: False positive for FileSystems.getDefault()
 
 ### 🚨 API Changes
 
 ### ✨ Merged pull requests
 * [#4965](https://github.com/pmd/pmd/pull/4965): \[java] Rename JUnit rules with overly restrictive names - [Juan Martín Sotuyo Dodero](https://github.com/jsotuyod) (@jsotuyod)
+* [#5225](https://github.com/pmd/pmd/pull/5225): \[java] Fix #5067: CloseResource: False positive for FileSystems.getDefault() - [Lukas Gräf](https://github.com/lukasgraef) (@lukasgraef)
 * [#5241](https://github.com/pmd/pmd/pull/5241): Ignore javacc code in coverage report - [Juan Martín Sotuyo Dodero](https://github.com/jsotuyod) (@jsotuyod)
 
 {% endtocmaker %}

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/rule/errorprone/CloseResourceRule.java

@@ -108,6 +108,7 @@ public class CloseResourceRule extends AbstractJavaRule {
                 .desc("Detect if 'close' (or other closeTargets) is called outside of a finally-block").defaultValue(false).build();
 
     private static final InvocationMatcher OBJECTS_NON_NULL = InvocationMatcher.parse("java.util.Objects#nonNull(_)");
+    private static final InvocationMatcher FILESYSTEMS_GET_DEFAULT = InvocationMatcher.parse("java.nio.file.FileSystems#getDefault()");
 
     private final Set<String> types = new HashSet<>();
     private final Set<String> simpleTypes = new HashSet<>();
@@ -204,6 +205,7 @@ private Map<ASTVariableId, TypeNode> getResourceVariables(ASTExecutableDeclarati
             .filter(this::isVariableNotSpecifiedInTryWithResource)
             .filter(var -> isResourceTypeOrSubtype(var) || isNodeInstanceOfResourceType(getTypeOfVariable(var)))
             .filterNot(var -> var.isAnnotationPresent("lombok.Cleanup"))
+            .filterNot(this::isDefaultFileSystem)
             .toList();
 
         for (ASTVariableId var : vars) {
@@ -499,6 +501,12 @@ private boolean isVariableNotSpecifiedInTryWithResource(ASTVariableId varId) {
         return tryStatement == null || !isVariableSpecifiedInTryWithResource(varId, tryStatement);
     }
 
+    private boolean isDefaultFileSystem(ASTVariableId varId) {
+        @Nullable
+        ASTExpression initializer = varId.getInitializer();
+        return FILESYSTEMS_GET_DEFAULT.matchesCall(initializer);
+    }
+
     private boolean isVariableSpecifiedInTryWithResource(ASTVariableId varId, ASTTryStatement tryWithResource) {
         // skip own resources - these are definitively closed
         if (tryWithResource.getResources().descendants(ASTVariableId.class).toList().contains(varId)) {

pmd-java/src/test/resources/net/sourceforge/pmd/lang/java/rule/errorprone/xml/CloseResource.xml

@@ -2044,6 +2044,20 @@ public class CastedParameter {
             // doesn't need to be closed, it's still a paramter…
         }
     }
+}
+        ]]></code>
+    </test-code>
+    <test-code>
+        <description>#5067: FileSystems.getDefault() can't be closed </description>
+        <expected-problems>0</expected-problems>
+        <code><![CDATA[
+import java.nio.file.FileSystem;
+import java.nio.file.FileSystems;
+
+public class DefaultFileSystemUsage {
+    public void useDefaultFS() {
+        FileSystem defaultFS = FileSystems.getDefault();
+    }
 }
         ]]></code>
     </test-code>