8231968: getCurrentThreadAllocatedBytes default implementation s/b getThreadAllocatedBytes

Pass Thread.currentThread().getId() to getThreadAllocatedBytes, remove its implSpec

Backport-of: 68e5c40

Author: Ekaterina Vergizova

src/jdk.management/share/classes/com/sun/management/ThreadMXBean.java

@@ -122,9 +122,6 @@ public interface ThreadMXBean extends java.lang.management.ThreadMXBean {
      *   {@link #getThreadAllocatedBytes getThreadAllocatedBytes}(Thread.currentThread().getId());
      * </pre></blockquote>
      *
-     * @implSpec The default implementation throws
-     * {@code UnsupportedOperationException}.
-     *
      * @return an approximation of the total memory allocated, in bytes, in
      * heap memory for the current thread
      * if thread memory allocation measurement is enabled;
@@ -141,7 +138,7 @@ public interface ThreadMXBean extends java.lang.management.ThreadMXBean {
      * @since 13.0.6
      */
     public default long getCurrentThreadAllocatedBytes() {
-        throw new UnsupportedOperationException();
+        return getThreadAllocatedBytes(Thread.currentThread().getId());
     }
 
     /**