BAEL-8219 Fix tests for core-java, maven and core-java-io projects

-Test fixes

core-java-io/src/test/java/com/baeldung/file/FilenameFilterManualTest.java

@@ -18,7 +18,7 @@ public class FilenameFilterManualTest {
     @BeforeClass
     public static void setupClass() {
         directory = new File(FilenameFilterManualTest.class.getClassLoader()
-            .getResource("testFolder")
+            .getResource("fileNameFilterManualTestFolder")
             .getFile());
     }