ICU-11067 documented limitation on modification while iterating

X-SVN-Rev: 36361

icu4j/main/classes/core/src/com/ibm/icu/text/UnicodeSet.java

@@ -4132,6 +4132,8 @@ public class UnicodeSet extends UnicodeFilter implements Iterable<String>, Compa
      * The UnicodeSet must not be altered during the iteration.
      * The EntryRange is the same each time; the contents are just reset.<br>
      * <b>Warning: </b>To iterate over the full contents, you have to also iterate over the strings.
+     * <p><b>Warning: </b>For speed, UnicodeSet iteration does not check for concurrent modification. 
+     * Do not alter the UnicodeSet while iterating.
      * 
      * <pre>
      * // Sample code
@@ -4180,6 +4182,8 @@ public class UnicodeSet extends UnicodeFilter implements Iterable<String>, Compa
 
     /**
      * Returns a string iterator. Uses the same order of iteration as {@link UnicodeSetIterator}.
+     * <p><b>Warning: </b>For speed, UnicodeSet iteration does not check for concurrent modification. 
+     * Do not alter the UnicodeSet while iterating.
      * @see java.util.Set#iterator()
      * @stable ICU 4.4
      */

icu4j/main/classes/core/src/com/ibm/icu/text/UnicodeSetIterator.java

@@ -32,6 +32,8 @@ import java.util.Iterator;
  *   }
  * }
  * </pre>
+ * <p><b>Warning: </b>For speed, UnicodeSet iteration does not check for concurrent modification. 
+ * Do not alter the UnicodeSet while iterating.
  * @author M. Davis
  * @stable ICU 2.0
  */
@@ -104,7 +106,8 @@ public class UnicodeSetIterator {
      * calls to <tt>next()</tt> and <tt>nextRange()</tt> without
      * calling <tt>reset()</tt> between them.  The results of doing so
      * are undefined.
-     *
+     * <p><b>Warning: </b>For speed, UnicodeSet iteration does not check for concurrent modification. 
+     * Do not alter the UnicodeSet while iterating.
      * @return true if there was another element in the set and this
      * object contains the element.
      * @stable ICU 2.0