refine javadoc about StringUtils.repeat(StringBuilder stringBuilder, final char ch, final int repeat), and make it private

Author: XenoAmess

src/main/java/org/apache/commons/lang3/StringUtils.java

@@ -6240,28 +6240,17 @@ public static String repeat(final char ch, final int repeat) {
     }
 
     /**
-     * <p>Returns padding using the specified delimiter repeated
-     * to a given length.</p>
+     * <p>Make the padding using the specified delimiter repeated
+     * to a given length, and fill the result to a StringBuilder</p>
      *
-     * <pre>
-     * StringUtils.repeat('e', 0)  = ""
-     * StringUtils.repeat('e', 3)  = "eee"
-     * StringUtils.repeat('e', -2) = ""
-     * </pre>
-     *
-     * <p>Note: this method does not support padding with
-     * <a href="http://www.unicode.org/glossary/#supplementary_character">Unicode Supplementary Characters</a>
-     * as they require a pair of {@code char}s to be represented.
-     * If you are needing to support full I18N of your applications
-     * consider using {@link #repeat(String, int)} instead.
-     * </p>
+     * This function works like {@code stringBuilder.append(repeat(ch,repeat))}, but runs faster.
      *
      * @param stringBuilder  stringBuilder to fill
      * @param ch  character to repeat
      * @param repeat  number of times to repeat char, negative treated as zero
-     * @see #repeat(String, int)
+     * @see #repeat(char, int)
      */
-    public static void repeat(StringBuilder stringBuilder, final char ch, final int repeat) {
+    private static void repeat(StringBuilder stringBuilder, final char ch, final int repeat) {
         for (int i = repeat - 1; i >= 0; i--) {
             stringBuilder.append(ch);
         }