After adding a warning for `{@link}` tags that refer to private/protected types, we see these warnings when building javadoc.

```
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java:1307: warning: reference to non-visible type: AbstractQueuedLongSynchronizer.acquire(AbstractQueuedLongSynchronizer.Node, long, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java:1350: warning: reference to non-visible type: AbstractQueuedLongSynchronizer.acquire(AbstractQueuedLongSynchronizer.Node, long, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java:1402: warning: reference to non-visible type: AbstractQueuedLongSynchronizer.acquire(AbstractQueuedLongSynchronizer.Node, long, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java:1446: warning: reference to non-visible type: AbstractQueuedLongSynchronizer.acquire(AbstractQueuedLongSynchronizer.Node, long, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedLongSynchronizer.java:1489: warning: reference to non-visible type: AbstractQueuedLongSynchronizer.acquire(AbstractQueuedLongSynchronizer.Node, long, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java:89: warning: reference to non-visible type: acquire(AbstractQueuedSynchronizer.Node, int, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
 * this object, and {@link #acquire}, given this saved state value,
                    ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java:1686: warning: reference to non-visible type: AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.Node, int, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java:1729: warning: reference to non-visible type: AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.Node, int, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java:1781: warning: reference to non-visible type: AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.Node, int, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java:1825: warning: reference to non-visible type: AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.Node, int, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
src/java.base/share/classes/java/util/concurrent/locks/AbstractQueuedSynchronizer.java:1868: warning: reference to non-visible type: AbstractQueuedSynchronizer.acquire(AbstractQueuedSynchronizer.Node, int, boolean, boolean, boolean, long) (use -protected or -private options to document non-public types)
         * {@link #acquire} with saved state as argument.
               ^
```