extract hasInvalidFiles() to VfsUtil

platform/core-api/src/com/intellij/openapi/vfs/VfsUtilCore.java

@@ -663,6 +663,15 @@ public class VfsUtilCore {
     return components;
   }
 
+  public static boolean hasInvalidFiles(@NotNull Iterable<VirtualFile> files) {
+    for (VirtualFile file : files) {
+      if (!file.isValid()) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   /**
    * this collection will keep only distinct files/folders, e.g. C:\foo\bar will be removed when C:\foo is added
    */

platform/indexing-impl/src/com/intellij/util/indexing/AdditionalIndexableFileSet.java

@@ -55,7 +55,7 @@ public class AdditionalIndexableFileSet implements IndexableFileSet {
 
   private Set<VirtualFile> getDirectories() {
     Set<VirtualFile> directories = cachedDirectories;
-    if (directories == null || filesInvalidated(directories) || filesInvalidated(cachedFiles)) {
+    if (directories == null || VfsUtilCore.hasInvalidFiles(directories) || VfsUtilCore.hasInvalidFiles(cachedFiles)) {
       directories = collectFilesAndDirectories();
     }
     return directories;
@@ -83,15 +83,6 @@ public class AdditionalIndexableFileSet implements IndexableFileSet {
     return directories;
   }
 
-  public static boolean filesInvalidated(Set<VirtualFile> files) {
-    for (VirtualFile file : files) {
-      if (!file.isValid()) {
-        return true;
-      }
-    }
-    return false;
-  }
-
   @Override
   public boolean isInSet(@NotNull VirtualFile file) {
     return VfsUtilCore.isUnder(file, getDirectories()) || cachedFiles.contains(file);