throw IllegalStateException as documented from validState()

git-svn-id: https://svn.apache.org/repos/asf/commons/proper/lang/trunk@983711 13f79535-47bb-0310-9956-ffa450edef68

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

@@ -765,7 +765,7 @@ public static <T extends CharSequence> T validIndex(T chars, int index) {
      */
     public static void validState(boolean expression) {
         if (expression == false) {
-            throw new IllegalArgumentException(DEFAULT_VALID_STATE_EX_MESSAGE);
+            throw new IllegalStateException(DEFAULT_VALID_STATE_EX_MESSAGE);
         }
     }