8298303: (fs) temporarily remove Path.getExtension

Reviewed-by: smarks, alanb

Author: Brian Burkhalter

src/java.base/share/classes/java/nio/file/Path.java

@@ -50,7 +50,7 @@
  * file system. {@code Path} defines the {@link #getFileName() getFileName},
  * {@link #getParent getParent}, {@link #getRoot getRoot}, and {@link #subpath
  * subpath} methods to access the path components or a subsequence of its name
- * elements, and {@link #getExtension() getExtension} to obtain its extension.
+ * elements.
  *
  * <p> In addition to accessing the components of a path, a {@code Path} also
  * defines the {@link #resolve(Path) resolve} and {@link #resolveSibling(Path)
@@ -249,63 +249,6 @@ public static Path of(URI uri) {
      */
     Path getFileName();
 
-    /**
-     * Returns the file extension of this path's file name as a {@code String}.
-     * The extension is derived from this {@code Path} by obtaining the
-     * {@linkplain #getFileName file name element}, deriving its {@linkplain
-     * #toString string representation}, and then extracting a substring
-     * determined by the position of a period character ('.', U+002E FULL STOP)
-     * within the file name string. If the file name element is {@code null},
-     * or if the file name string does not contain a period character, or if
-     * the only period in the file name string is its first character, then
-     * the extension is {@code null}. Otherwise, the extension is the substring
-     * after the last period in the file name string. If this last period is
-     * also the last character in the file name string, then the  extension is
-     * {@linkplain String#isEmpty empty}.
-     *
-     * @implSpec
-     * The default implementation is equivalent for this path to:
-     * <pre>{@code
-     * int lastPeriod = fileName.lastIndexOf('.');
-     * if (lastPeriod <= 0)
-     *     return null;
-     * return (lastPeriod == fileName.length() - 1)
-     *     ? ""
-     *     : fileName.substring(lastPeriod + 1);
-     * }</pre>
-     *
-     * @return  the file name extension of this path, which might be the
-     *          empty string, or {@code null} if no extension is found
-     *
-     * @since 20
-     */
-    default String getExtension() {
-        Path fileName = getFileName();
-        if (fileName == null)
-            return null;
-
-        String fileNameString = fileName.toString();
-        int length = fileNameString.length();
-
-        // An empty or unity length file name string has a null extension
-        if (length > 1) {
-            int lastPeriodIndex = fileNameString.lastIndexOf('.');
-
-            // Indeterminate if there is no period character or
-            // only the first character is a period character
-            if (lastPeriodIndex > 0) {
-                if (lastPeriodIndex == length - 1) {
-                    // empty string
-                    return "";
-                } else {
-                    return fileNameString.substring(lastPeriodIndex + 1);
-                }
-            }
-        }
-
-        return null;
-    }
-
     /**
      * Returns the <em>parent path</em>, or {@code null} if this path does not
      * have a parent.