fix an edge case in RemoveUnusedProperties when there is no parent in filtering (#6687)

* rewrite-maven/RemoveUnusedProperties: fixing an edge case which would throw if a singular/root pom (no parent in the in-memory relative path) included resource filtering

* Minimize test

---------

Co-authored-by: Tim te Beek <tim@moderne.io>

Author: nmck257

rewrite-maven/src/main/java/org/openrewrite/maven/RemoveUnusedProperties.java

@@ -238,7 +238,7 @@ public Xml.Tag visitTag(Xml.Tag tag, ExecutionContext ctx) {
                         directory != null) {
                     Path path = getCursor().firstEnclosingOrThrow(SourceFile.class).getSourcePath();
                     try {
-                        acc.filteredResourcePathsToDeclaringPoms.put(path.getParent().resolve(directory), getResolutionResult());
+                        acc.filteredResourcePathsToDeclaringPoms.put(path.resolveSibling(directory), getResolutionResult());
                     } catch (InvalidPathException ignored) {
                     } // fail quietly
                 }

rewrite-maven/src/test/java/org/openrewrite/maven/RemoveUnusedPropertiesTest.java

@@ -19,6 +19,7 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
 import org.openrewrite.DocumentExample;
+import org.openrewrite.Issue;
 import org.openrewrite.test.RecipeSpec;
 import org.openrewrite.test.RewriteTest;
 
@@ -842,4 +843,55 @@ void removesIrrelevantPropertyDeclarationForFilteredResourceUsage() {
           )
         );
     }
+
+    @Issue("https://github.com/openrewrite/rewrite/pull/6687")
+    @Test
+    void removesUnusedPropertiesInSinglePomWithResourceFilteringEnabled() {
+        rewriteRun(
+          pomXml(
+            """
+            <project>
+              <modelVersion>4.0.0</modelVersion>
+              <groupId>com.sample</groupId>
+              <artifactId>test.application</artifactId>
+              <version>1.0.0</version>
+              <name>test-application</name>
+              <packaging>jar</packaging>
+            
+              <properties>
+                <junk>junk</junk>
+              </properties>
+            
+              <build>
+                <resources>
+                  <resource>
+                    <directory>src/main/resources</directory>
+                    <filtering>true</filtering>
+                  </resource>
+                </resources>
+              </build>
+            </project>
+            """,
+            """
+            <project>
+              <modelVersion>4.0.0</modelVersion>
+              <groupId>com.sample</groupId>
+              <artifactId>test.application</artifactId>
+              <version>1.0.0</version>
+              <name>test-application</name>
+              <packaging>jar</packaging>
+            
+              <build>
+                <resources>
+                  <resource>
+                    <directory>src/main/resources</directory>
+                    <filtering>true</filtering>
+                  </resource>
+                </resources>
+              </build>
+            </project>
+            """
+          )
+        );
+    }
 }