Files.move throws DirectoryNotEmptyException when moving directory across file system

Summary

Amend the verbiage describing when java.nio.file.Files.move() will throw the optional specific exception DirectoryNotEmptyException.

Problem

java.nio.file.Files.move() throws a DirectoryNotEmptyException when the source directory contains entries which would be required to be moved if the move is to another file system (device) but this situation is not explicitly described in the javadoc.

Solution

Include in the javadoc for java.nio.file.Files.move() that it will throw the optional specific exception DirectoryNotEmptyException in the case where the source directory is non-empty and the target is on another file system.

Specification

--- a/src/java.base/share/classes/java/nio/file/Files.java
+++ b/src/java.base/share/classes/java/nio/file/Files.java
@@ -1391,8 +1391,9 @@
      *          specific exception)</i>
      * @throws  DirectoryNotEmptyException
      *          the {@code REPLACE_EXISTING} option is specified but the file
-     *          cannot be replaced because it is a non-empty directory
-     *          <i>(optional specific exception)</i>
+     *          cannot be replaced because it is a non-empty directory, or the
+     *          source is a non-empty directory containing entries that would
+     *          be required to be moved <i>(optional specific exceptions)</i>
      * @throws  AtomicMoveNotSupportedException
      *          if the options array contains the {@code ATOMIC_MOVE} option but
      *          the file cannot be moved as an atomic file system operation.