6426678: (spec) File.createTempFile(prefix, suffix, dir) needs clarification for illegal symbols in suffix

Reviewed-by: alanb

Author: Brian Burkhalter

src/java.base/share/classes/java/io/File.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 1994, 2023, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1994, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -2117,6 +2117,11 @@ static File generateFile(String prefix, String suffix, File dir)
      * made the name of the new file will be generated by concatenating the
      * prefix, five or more internally-generated characters, and the suffix.
      *
+     * <p> If a file with the generated name cannot be created by the
+     * underlying platform, then an {@code IOException} will be thrown.
+     * This could occur for example if the supplied prefix or suffix contains
+     * one or more characters not supported by the underlying file system.
+     *
      * <p> If the {@code directory} argument is {@code null} then the
      * system-dependent default temporary-file directory will be used.  The
      * default temporary-file directory is specified by the system property