Java: update qhelp recommendation and example

java/ql/src/Violations of Best Practice/Undesirable Calls/DoNotCallFinalize.md

@@ -4,14 +4,43 @@ Triggering garbage collection by directly calling `finalize()` may either have n
 
 ## Recommendation
 
-Avoid calling `finalize()` in application code. Allow the JVM to determine a garbage collection schedule instead.
+Avoid calling `finalize()` in application code. Allow the JVM to determine a garbage collection schedule instead. If you need to explicitly release resources, provide a specific method to do so, such as by implementing the `AutoCloseable` interface and overriding its `close` method. You can then use a `try-with-resources` block to ensure that the resource is closed.
 
 ## Example
 
 ```java
-public class Test {
-    void f() throws Throwable {
-        this.finalize(); // NON_COMPLIANT
+class LocalCache {
+    private Collection<File> cacheFiles = ...;
+    // ...
+}
+
+void main() {
+    LocalCache cache = new LocalCache();
+    // ...
+    cache.finalize(); // NON_COMPLIANT
+}
+
+```
+
+```java
+import java.lang.AutoCloseable;
+import java.lang.Override;
+
+class LocalCache implements AutoCloseable {
+    private Collection<File> cacheFiles = ...;
+    // ...
+
+    @Override
+    public void close() throws Exception {
+        // release resources here if required
+    }
+}
+
+void main() {
+    // COMPLIANT: uses try-with-resources to ensure that
+    // a resource implementing AutoCloseable is closed.
+    try (LocalCache cache = new LocalCache()) {
+        // ...
     }
 }
 
@@ -25,4 +54,6 @@ This rule is focused on the use of existing `finalize()` invocations rather than
 
 - SEI CERT Oracle Coding Standard for Java: [MET12-J. Do not use finalizers](https://wiki.sei.cmu.edu/confluence/display/java/MET12-J.+Do+not+use+finalizers).
 - Java API Specification: [Object.finalize()](https://docs.oracle.com/javase/10/docs/api/java/lang/Object.html#finalize()).
+- Java API Specification: [Interface AutoCloseable](https://docs.oracle.com/javase/10/docs/api/java/lang/AutoCloseable.html).
+- Java SE Documentation: [The try-with-resources Statement](https://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html).
 - Common Weakness Enumeration: [CWE-586](https://cwe.mitre.org/data/definitions/586).