Null safe

Signed-off-by: tobiasKaminsky <tobias@kaminsky.me>

src/androidTest/java/com/owncloud/android/ui/fragment/OCFileListFragmentStaticServerIT.kt

@@ -223,6 +223,11 @@ class OCFileListFragmentStaticServerIT : AbstractIT() {
             sut.adapter.swapDirectory(user, testFolder, activity.storageManager, false, "")
             Assert.assertFalse(sut.adapter.shouldShowHeader())
 
+            testFolder.richWorkspace = null
+            activity.storageManager.saveFile(testFolder)
+            sut.adapter.swapDirectory(user, testFolder, activity.storageManager, false, "")
+            Assert.assertFalse(sut.adapter.shouldShowHeader())
+
             testFolder.richWorkspace = "1"
             activity.storageManager.saveFile(testFolder)
             sut.adapter.setCurrentDirectory(testFolder)

src/main/java/com/owncloud/android/ui/adapter/OCFileListAdapter.java

@@ -851,6 +851,10 @@ public class OCFileListAdapter extends RecyclerView.Adapter<RecyclerView.ViewHol
             return false;
         }
 
+        if (currentDirectory.getRichWorkspace() == null) {
+            return false;
+        }
+
         return !TextUtils.isEmpty(currentDirectory.getRichWorkspace().trim());
     }