Index: lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/KeywordRepeatFilterFactory.java
===================================================================
--- lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/KeywordRepeatFilterFactory.java	(revision 1454344)
+++ lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/KeywordRepeatFilterFactory.java	(working copy)
@@ -22,11 +22,17 @@
 
 /**
  * Factory for {@link KeywordRepeatFilter}.
+ *
+ * Since {@link KeywordRepeatFilter} emits two tokens for every input token, and any tokens that aren't transformed
+ * later in the analysis chain will be in the document twice. Therefore, consider adding
+ * {@link RemoveDuplicatesTokenFilterFactory} later in the analysis chain, e.g.
  * <pre class="prettyprint" >
  * &lt;fieldType name="text_keyword" class="solr.TextField" positionIncrementGap="100"&gt;
  *   &lt;analyzer&gt;
  *     &lt;tokenizer class="solr.WhitespaceTokenizerFactory"/&gt;
  *     &lt;filter class="solr.KeywordRepeatFilter"/&gt;
+ *     &lt;filter class="solr.PorterStemFilterFactory"/&gt;
+ *     &lt;filter class="solr.RemoveDuplicatesTokenFilterFactory"/&gt;
  *   &lt;/analyzer&gt;
  * &lt;/fieldType&gt;</pre>
  */
Index: lucene/analysis/common/src/java/org/apache/lucene/analysis/snowball/SnowballFilter.java
===================================================================
--- lucene/analysis/common/src/java/org/apache/lucene/analysis/snowball/SnowballFilter.java	(revision 1454344)
+++ lucene/analysis/common/src/java/org/apache/lucene/analysis/snowball/SnowballFilter.java	(working copy)
@@ -37,6 +37,18 @@
  *  <li>For other languages, see {@link LowerCaseFilter}.
  * </ul>
  * </p>
+ *
+ * <p>
+ * Note: This filter is aware of the {@link KeywordAttribute}. To prevent
+ * certain terms from being passed to the stemmer
+ * {@link KeywordAttribute#isKeyword()} should be set to <code>true</code>
+ * in a previous {@link TokenStream}.
+ *
+ * Note: For including the original term as well as the stemmed version, see
+ * {@link org.apache.lucene.analysis.miscellaneous.KeywordRepeatFilterFactory}
+ * </p>
+ *
+ *
  */
 public final class SnowballFilter extends TokenFilter {
 
Index: lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java
===================================================================
--- lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java	(revision 1454344)
+++ lucene/analysis/common/src/java/org/apache/lucene/analysis/hunspell/HunspellStemFilter.java	(working copy)
@@ -30,6 +30,18 @@
 /**
  * TokenFilter that uses hunspell affix rules and words to stem tokens.  Since hunspell supports a word having multiple
  * stems, this filter can emit multiple tokens for each consumed token
+ *
+ * <p>
+ * Note: This filter is aware of the {@link KeywordAttribute}. To prevent
+ * certain terms from being passed to the stemmer
+ * {@link KeywordAttribute#isKeyword()} should be set to <code>true</code>
+ * in a previous {@link TokenStream}.
+ *
+ * Note: For including the original term as well as the stemmed version, see
+ * {@link org.apache.lucene.analysis.miscellaneous.KeywordRepeatFilterFactory}
+ * </p>
+ *
+ *
  */
 public final class HunspellStemFilter extends TokenFilter {
   
Index: lucene/analysis/common/src/java/org/apache/lucene/analysis/en/PorterStemFilter.java
===================================================================
--- lucene/analysis/common/src/java/org/apache/lucene/analysis/en/PorterStemFilter.java	(revision 1454344)
+++ lucene/analysis/common/src/java/org/apache/lucene/analysis/en/PorterStemFilter.java	(working copy)
@@ -48,6 +48,9 @@
     certain terms from being passed to the stemmer
     {@link KeywordAttribute#isKeyword()} should be set to <code>true</code>
     in a previous {@link TokenStream}.
+
+    Note: For including the original term as well as the stemmed version, see
+   {@link org.apache.lucene.analysis.miscellaneous.KeywordRepeatFilterFactory}
     </p>
 */
 public final class PorterStemFilter extends TokenFilter {
Index: lucene/analysis/common/src/java/org/apache/lucene/analysis/en/KStemFilter.java
===================================================================
--- lucene/analysis/common/src/java/org/apache/lucene/analysis/en/KStemFilter.java	(revision 1454344)
+++ lucene/analysis/common/src/java/org/apache/lucene/analysis/en/KStemFilter.java	(working copy)
@@ -32,6 +32,18 @@
  * Conference on Research and Development in Information Retrieval, 191-203, 1993).
  * <p/>
  * All terms must already be lowercased for this filter to work correctly.
+ *
+ * <p>
+ * Note: This filter is aware of the {@link KeywordAttribute}. To prevent
+ * certain terms from being passed to the stemmer
+ * {@link KeywordAttribute#isKeyword()} should be set to <code>true</code>
+ * in a previous {@link TokenStream}.
+ *
+ * Note: For including the original term as well as the stemmed version, see
+ * {@link org.apache.lucene.analysis.miscellaneous.KeywordRepeatFilterFactory}
+ * </p>
+ *
+ *
  */
 
 public final class KStemFilter extends TokenFilter {