java: further <p> fixes

javadoc's HTML parser seems more limited, so just close <p> blocks
before opening <pre> or <ol>.

Followup of commit f4186a7a49.

generator/java.ml

@@ -48,12 +48,12 @@ import java.util.Map;
  * </p><p>
  * Note that the main documentation for the libguestfs API is in
  * the following man pages:
- * </p><p>
+ * </p>
  * <ol>
  * <li> <a href=\"http://libguestfs.org/guestfs-java.3.html\"><code>guestfs-java(3)</code></a> and </li>
  * <li> <a href=\"http://libguestfs.org/guestfs.3.html\"><code>guestfs(3)</code></a>. </li>
  * </ol>
- * </p><p>
+ * <p>
  * This javadoc is <b>not</b> a good introduction to using libguestfs.
  * </p>
  *
@@ -180,6 +180,7 @@ public class GuestFS {
    * </p><p>
    * When an event happens, the callback object's <code>event</code> method
    * is invoked like this:
+   * </p>
    * <pre>
    * callback.event (event,    // the specific event which fired (long)
    *                 eh,       // the event handle (int)
@@ -187,6 +188,7 @@ public class GuestFS {
    *                 array     // event data (long[])
    *                 );
    * </pre>
+   * <p>
    * Note that you can pass arbitrary data from the main program to the
    * callback by putting it into your {@link EventCallback callback object},
    * then accessing it in the callback via <code>this</code>.