DROOLS-5264: Clear selected file when dialog is closed

This PR clear the last selected file from file selector widget when the dialog for artifact upload is closed or canceled.

For more details see: https://issues.redhat.com/browse/DROOLS-5264

uberfire-m2repo-editor/uberfire-m2repo-editor-client/src/main/java/org/guvnor/m2repo/client/upload/UploadFormViewImpl.java

@@ -202,6 +202,18 @@ public String getFileName() {
         return uploader.getFilename();
     }
 
+    @Override
+    public void hide() {
+        super.hide();
+        uploader.clear();
+    }
+
+    @Override
+    public void removeFromParent() {
+        super.removeFromParent();
+        uploader.clear();
+    }
+
     private void showMessage(final String message) {
         Window.alert(message);
     }

uberfire-m2repo-editor/uberfire-m2repo-editor-client/src/test/java/org/guvnor/m2repo/client/upload/UploadFormViewImplTest.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2020 Red Hat, Inc. and/or its affiliates.
+ *
+ * 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.guvnor.m2repo.client.upload;
+
+import com.google.gwtmockito.GwtMockitoTestRunner;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.uberfire.ext.widgets.common.client.common.FileUpload;
+
+import static org.mockito.Mockito.doCallRealMethod;
+import static org.mockito.Mockito.verify;
+
+@RunWith(GwtMockitoTestRunner.class)
+public class UploadFormViewImplTest {
+
+    @Mock
+    private FileUpload uploader;
+
+    @Mock
+    private UploadFormViewImpl testedView;
+
+    @Before
+    public void setUp() throws Exception {
+        testedView.uploader = uploader;
+    }
+
+    @Test
+    public void testHide() {
+        doCallRealMethod().when(testedView).hide();
+
+        testedView.hide();
+
+        verify(uploader).clear();
+    }
+
+    @Test
+    public void testRemoveFromParent() {
+        doCallRealMethod().when(testedView).removeFromParent();
+
+        testedView.removeFromParent();
+
+        verify(uploader).clear();
+    }
+}