[wpiutil] Add WPICleaner and an example how to use it (#4850)

wpiutil/src/main/java/edu/wpi/first/util/WPICleaner.java

@@ -0,0 +1,28 @@
+// Copyright (c) FIRST and other WPILib contributors.
+// Open Source Software; you can modify and/or share it under the terms of
+// the WPILib BSD license file in the root directory of this project.
+
+package edu.wpi.first.util;
+
+import java.lang.ref.Cleaner;
+import java.lang.ref.Cleaner.Cleanable;
+
+/** Cleaner object for WPILib objects. */
+public final class WPICleaner {
+  private WPICleaner() {
+    throw new UnsupportedOperationException("This is a utility class!");
+  }
+
+  private static final Cleaner instance = Cleaner.create();
+
+  /**
+   * Register an object with the cleaner.
+   *
+   * @param object The object to register.
+   * @param runnable The runnable to call on cleanup.
+   * @return The registered Cleanable.
+   */
+  public static Cleanable register(Object object, Runnable runnable) {
+    return instance.register(object, runnable);
+  }
+}