Correct native charset in TestWorkspaceEncodingExistingWorkspace ecli…

…pse-platform#128

TestWorkspaceEncodingExistingWorkspace retrieves the expected native
charset via the "file.encoding" system property, but with Java 21 this
always returns UTF-8 and the native encoding can be retrieved via
"native.encoding" since Java 17. This change adapts the test to properly
run with Java 21.

Fixes eclipse-platform#128

resources/tests/org.eclipse.core.tests.resources/src/org/eclipse/core/tests/resources/session/TestWorkspaceEncodingExistingWorkspace.java

@@ -48,7 +48,7 @@ public TestWorkspaceEncodingExistingWorkspace() {
 	}
 
 	public void testExpectedEncoding1() throws Exception {
-		String defaultValue = System.getProperty("file.encoding");
+		String defaultValue = System.getProperty("native.encoding");
 		IWorkspace workspace = ResourcesPlugin.getWorkspace();
 
 		// Should be system default