document list is unmodifiable

Author: mina86

src/main/java/org/apache/commons/csv/CSVRecord.java

@@ -28,6 +28,10 @@
 
 /**
  * A CSV record parsed from a CSV file.
+ *
+ * <p>The class implements {@link List} interface but does not allow
+ * modifications, i.e. all destructive operations (such as {@link List#add} or
+ * even {@link List#set}) throw {@link UnsupportedOperationException}.
  */
 public final class CSVRecord extends AbstractList<String> implements Serializable {