[699] Introduce an interface to persist RepresentationMetadata

Bug: #699
Signed-off-by: Stéphane Bégaudeau <[email protected]>

CHANGELOG.adoc

@@ -50,6 +50,7 @@ See ADR-54 for the details.
 - https://github.com/eclipse-sirius/sirius-components/issues/1138[#1138] [workbench] The left and right panels can be closed by clicking on the current view's icon or by resizing them to the minimum widht (showing only the icons).
 When closed, clicking on any of the views' icon will re-open the panel to make the selected view visible.
 - https://github.com/eclipse-sirius/sirius-components/issues/689[#689] [diagram] Add a variable containing objects ids to render for unsynchronized nodes rendering
+- https://github.com/eclipse-sirius/sirius-components/issues/699[#699] [core] Introduce an interface to let integrators persist `RepresentationMetadata`. Thanks to this first step, it should be soon possible to create representations which do not persist anything more than their metadata. Sirius Components will not provide an implementation of this interface since its behavior is specific to the persistence layer of the application integrating Sirius Components but it may start to use it soon. When this interface will be used, its implementation will be required by those who are integrating Sirius Components in their application. The `Form` representation may be a very good candidate for this interface. Widespread usage of this new interface should be the final nail necessary to remove the metadata fields from the representation objects (`Diagram`, `Form`, `Selection`, `Validation`, etc)
 
 === New features
 

backend/sirius-components-core/src/main/java/org/eclipse/sirius/components/core/api/IRepresentationMetadataPersistenceService.java

@@ -0,0 +1,40 @@
+/*******************************************************************************
+ * Copyright (c) 2022 Obeo.
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *     Obeo - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.sirius.components.core.api;
+
+import org.eclipse.sirius.components.core.RepresentationMetadata;
+
+/**
+ * Used to persist representation metadata.
+ *
+ * @author sbegaudeau
+ */
+public interface IRepresentationMetadataPersistenceService {
+
+    void save(IEditingContext editingContext, RepresentationMetadata representationMetadata);
+
+    /**
+     * Implementation which does nothing, used for mocks in unit tests.
+     *
+     * @author sbegaudeau
+     */
+    class NoOp implements IRepresentationMetadataPersistenceService {
+
+        @Override
+        public void save(IEditingContext editingContext, RepresentationMetadata representationMetadata) {
+            // Do nothing
+        }
+
+    }
+
+}