added a loading node for use when child nodes are still being loaded

Core/src/org/sleuthkit/autopsy/datamodel/CommonFileChildNode.java

@@ -112,5 +112,6 @@ public class CommonFileChildNode extends FileNode {
         public String toString() {
             return displayString;
         }
-    }
+    }   
+    
 }

Core/src/org/sleuthkit/autopsy/datamodel/CommonFileChildNodeLoading.java

@@ -0,0 +1,48 @@
+/*
+ * 
+ * Autopsy Forensic Browser
+ * 
+ * Copyright 2018 Basis Technology Corp.
+ * Contact: carrier <at> sleuthkit <dot> org
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * 
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.sleuthkit.autopsy.datamodel;
+
+import org.openide.nodes.Children;
+
+/**
+ * A dummy node used by the child factory to display while children are being
+ * generated
+ */
+public class CommonFileChildNodeLoading extends DisplayableItemNode {
+
+    public CommonFileChildNodeLoading(Children children) {
+        super(children);
+    }
+
+    @Override
+    public <T> T accept(DisplayableItemNodeVisitor<T> visitor) {
+        return visitor.visit(this);
+    }
+
+    @Override
+    public boolean isLeafTypeNode() {
+        return true;
+    }
+
+    @Override
+    public String getItemType() {
+        return getClass().getName();
+    }
+}

Core/src/org/sleuthkit/autopsy/datamodel/CommonFileParentNode.java

@@ -140,6 +140,11 @@ public class CommonFileParentNode extends DisplayableItemNode {
             list.addAll(this.descendants);
             return true;
         }
+        
+        @Override 
+        protected Node createWaitNode(){
+            return new CommonFileChildNodeLoading(Children.LEAF);
+        }
     }
 
     @NbBundle.Messages({

Core/src/org/sleuthkit/autopsy/datamodel/DisplayableItemNodeVisitor.java

@@ -115,6 +115,8 @@ public interface DisplayableItemNodeVisitor<T> {
     T visit (CommonFilesSearchNode cfsn);
     
     T visit (CommonFileChildNode cfcn);
+    
+    T visit (CommonFileChildNodeLoading cfcnl);
 
     /*
      * Tags
@@ -199,6 +201,11 @@ public interface DisplayableItemNodeVisitor<T> {
             return defaultVisit(cfsn);
         }
         
+        @Override
+        public T visit(CommonFileChildNodeLoading cfcnl){
+            return defaultVisit(cfcnl);
+        }
+        
         @Override
         public T visit(DirectoryNode dn) {
             return defaultVisit(dn);