Bug 581321 - [GroupBy] list order changed after grouping a filtered list

Extended the regression fix for a possible ClassCastException so that
the groupBy structure is ALWAYS removed prior to removing the sort and
filter state, before the groupBy configuration is updated.

Signed-off-by: Dirk Fauth <dirk.fauth@googlemail.com>

Change-Id: Ibbd832fcaab4d019c714ce537eb15a9e3f5c514b

3 files changed, 11 insertions, 36 deletions

diff --git a/org.eclipse.nebula.widgets.nattable.extension.glazedlists/.settings/.api_filters b/org.eclipse.nebula.widgets.nattable.extension.glazedlists/.settings/.api_filters
deleted file mode 100644
index 29182a8f..00000000
--- a/org.eclipse.nebula.widgets.nattable.extension.glazedlists/.settings/.api_filters
+++ /dev/null
@@ -1,11 +0,0 @@
-<?xml version="1.0" encoding="UTF-8" standalone="no"?>
-<component id="org.eclipse.nebula.widgets.nattable.extension.glazedlists" version="2">
-    <resource path="src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByModel.java" type="org.eclipse.nebula.widgets.nattable.extension.glazedlists.groupBy.GroupByModel">
-        <filter id="336658481">
-            <message_arguments>
-                <message_argument value="org.eclipse.nebula.widgets.nattable.extension.glazedlists.groupBy.GroupByModel"/>
-                <message_argument value="LOAD_STATE_INDICATOR"/>
-            </message_arguments>
-        </filter>
-    </resource>
-</component>
diff --git a/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByDataLayer.java b/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByDataLayer.java
index e9247810..d8419b0a 100644
--- a/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByDataLayer.java
+++ b/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByDataLayer.java
@@ -640,18 +640,15 @@ public class GroupByDataLayer<T> extends DataLayer implements Observer {
         // structure costs time
         BusyIndicator.showWhile(Display.getDefault(), () -> {
             List<Integer> indexes = new ArrayList<>();
-            if (GroupByModel.LOAD_STATE_INDICATOR.equals(arg)) {
-                // if the GroupByModel was loaded and not simply updated, there
-                // can be situations where the groupby indexes and the
-                // corresponding types per column are totally different. In this
-                // case we first need to perform a clear operation without the
-                // new groupby configuration, and then re-apply everything.
-                // Otherwise the filter operation might trigger a list update
-                // which then leads to ClassCastExceptions as the old
-                // GroupByObjects are still in the TreeList.
-                indexes.addAll(this.groupByModel.getGroupByColumnIndexes());
-                this.groupByModel.getGroupByColumnIndexes().clear();
-            }
+            // there can be situations where the groupby indexes and the
+            // corresponding types per column are totally different. In this
+            // case we first need to perform a clear operation without the
+            // new groupby configuration, and then re-apply everything.
+            // Otherwise the filter operation might trigger a list update
+            // which then leads to ClassCastExceptions as the old
+            // GroupByObjects are still in the TreeList.
+            indexes.addAll(this.groupByModel.getGroupByColumnIndexes());
+            this.groupByModel.getGroupByColumnIndexes().clear();
 
             // if we know the sort model, we need to clear the sort model to
             // avoid strange side effects while updating the tree structure
@@ -686,9 +683,7 @@ public class GroupByDataLayer<T> extends DataLayer implements Observer {
                 this.filterRowDataProvider.getFilterStrategy().applyFilter(original);
             }
 
-            if (GroupByModel.LOAD_STATE_INDICATOR.equals(arg)) {
-                this.groupByModel.getGroupByColumnIndexes().addAll(indexes);
-            }
+            this.groupByModel.getGroupByColumnIndexes().addAll(indexes);
 
             updateTree();
 
diff --git a/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByModel.java b/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByModel.java
index f34c9de7..715ab72f 100644
--- a/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByModel.java
+++ b/org.eclipse.nebula.widgets.nattable.extension.glazedlists/src/org/eclipse/nebula/widgets/nattable/extension/glazedlists/groupBy/GroupByModel.java
@@ -29,15 +29,6 @@ public class GroupByModel extends Observable implements IPersistable {
 
     public static final String PERSISTENCE_KEY_GROUP_BY_COLUMN_INDEXES = ".groupByColumnIndexes"; //$NON-NLS-1$
 
-    /**
-     * Argument that is passed to {@link #notifyObservers(Object)} to inform
-     * about a complete change. Needed to handle the tree update slightly
-     * different.
-     *
-     * @since 2.1
-     */
-    public static final String LOAD_STATE_INDICATOR = "LOAD_STATE"; //$NON-NLS-1$
-
     private List<Integer> groupByColumnIndexes = new ArrayList<>();
 
     /**
@@ -122,7 +113,7 @@ public class GroupByModel extends Observable implements IPersistable {
         }
 
         setChanged();
-        notifyObservers(LOAD_STATE_INDICATOR);
+        notifyObservers();
     }
 
     /**