Avoid failures in SourceTest when filesystem does not support unicode paths

Author: vlsi

core/src/test/java/org/apache/calcite/util/SourceTest.java

@@ -111,7 +111,11 @@ void testAbsoluteFileToUrl(String path, String expectedUrl) throws URISyntaxExce
     URL url = of(absoluteFile).url();
 
     assertNotNull(url, () -> "No URL generated for Sources.of(file(" + path + ").absoluteFile)");
-    assertEquals(absoluteFile.getAbsolutePath(), Sources.of(url).file().getPath(),
+    // Sources.of(url).file().getPath() does not always work
+    // e.g. it might throw java.nio.file.InvalidPathException: Malformed input or input contains
+    // unmappable characters: /home/.../ws/core/????????? ?????? ??????? ?????.txt
+    //        at java.base/sun.nio.fs.UnixPath.encode(UnixPath.java:145)
+    assertEquals(absoluteFile.getAbsolutePath(), url.toURI().getSchemeSpecificPart(),
         () -> "Sources.of(Sources.of(file(" + path + ").absolutePath).url()).file().getPath()");
   }