Fix ReportConfigurationPanel lambda serialization

A filter in ReportConfigurationPanel was not serializable;
fixed by replacing lambda with resulting objects.

gui/admin-gui/src/main/java/com/evolveum/midpoint/gui/api/model/ReadOnlyValueModel.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2010-2018 Evolveum
+ *
+ * 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 com.evolveum.midpoint.gui.api.model;
+
+import org.apache.wicket.model.AbstractReadOnlyModel;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * EXPERIMENTAL
+ * TODO better name
+ *
+ * @author mederly
+ */
+public class ReadOnlyValueModel<T> extends AbstractReadOnlyModel<T> {
+
+	@NotNull private final T object;
+
+	public ReadOnlyValueModel(@NotNull T object) {
+		this.object = object;
+	}
+
+	@Override
+	public T getObject() {
+		return object;
+	}
+}

gui/admin-gui/src/main/java/com/evolveum/midpoint/gui/api/util/WebComponentUtil.java

@@ -46,7 +46,7 @@
 import javax.xml.namespace.QName;
 
 import com.evolveum.midpoint.gui.api.SubscriptionType;
-import com.evolveum.midpoint.gui.api.model.ReadOnlyModel;
+import com.evolveum.midpoint.gui.api.model.ReadOnlyValueModel;
 import com.evolveum.midpoint.model.api.ModelExecuteOptions;
 import com.evolveum.midpoint.schema.GetOperationOptions;
 import com.evolveum.midpoint.schema.SelectorOptions;
@@ -701,9 +701,10 @@ public List<T> getObject() {
 		};
 	}
 
+	// use for small enums only
 	@NotNull
-	public static <T extends Enum> IModel<List<T>> createReadonlyModelFromEnum(@NotNull Class<T> type, @NotNull Predicate<T> filter) {
-		return new ReadOnlyModel<>(() ->
+	public static <T extends Enum> IModel<List<T>> createReadonlyValueModelFromEnum(@NotNull Class<T> type, @NotNull Predicate<T> filter) {
+		return new ReadOnlyValueModel<>(
 				Arrays.stream(type.getEnumConstants())
 						.filter(filter)
 						.collect(Collectors.toList()));

gui/admin-gui/src/main/java/com/evolveum/midpoint/web/page/admin/reports/component/ReportConfigurationPanel.java

@@ -69,7 +69,7 @@ protected void initLayout() {
                 createStringResource("ObjectType.description"), ID_LABEL_SIZE, ID_INPUT_SIZE, false);
         add(description);
 
-        IModel choices = WebComponentUtil.createReadonlyModelFromEnum(ExportType.class, e -> e != ExportType.JXL);
+        IModel choices = WebComponentUtil.createReadonlyValueModelFromEnum(ExportType.class, e -> e != ExportType.JXL);
         IChoiceRenderer renderer = new EnumChoiceRenderer();
         DropDownFormGroup exportType = new DropDownFormGroup(ID_EXPORT_TYPE, new PropertyModel<ExportType>(getModel(), ReportDto.F_EXPORT_TYPE), choices, renderer,
                 createStringResource("ReportType.export"), ID_LABEL_SIZE, ID_INPUT_SIZE, true);