[1018] Rework library loading to be extensible and re-usable

* Move our library loading code into SysONLibraryLoader, which
downstream applications may re-use to load their own libraries from the
classpath.
* Also make the library loading unit tests rely on them.
* Make internal methods of SysMLStandardLibrariesConfiguration protected
instead of private so it can be easily extended/redefined.
* The list of EPackages to register, and of libraries to load, are now
defined in their own protected method so as to be easily redefined.
* Move KerML/SysML standard libraries loading out of the constructor of
the @configuration. Now the standard libraries get loaded when they are
needed for the first time. Downstream applications may choose this
moment to be at application start, or, by default, at the latest time
possible, that is, when first opening a SysML project.
* Rename 'SysMLStandardLibrariesConfiguration' into
'SysONDefaultLibrariesConfiguration' to reflect the fact that default
libraries may include non-standard libraries and that it is up to the
application to determine which libraries are the default ones.
* Update changelog and release notes accordingly.

Bug: #1018
Signed-off-by: Florent Latombe <florent.latombe@obeo.fr>

Author: flatombe

CHANGELOG.adoc

@@ -10,6 +10,7 @@
 * A new service has been added to centralize the behavior of moving semantic elements in _org.eclipse.syson.services.api.ISysMLMoveElementService_.
 It replaces the public methods _UtilService.moveMembership_ and _ToolService.moveSemanticElement_
 * A new service has been added to centralize the verification of read-only elements in _org.eclipse.syson.services.api.ISysMLReadOnlyService_.
+- https://github.com/eclipse-syson/syson/issues/1018[#1018] `SysMLStandardLibrariesConfiguration` has been refactored and renamed `SysONDefaultLibrariesConfiguration`.
 
 
 === Dependency update
@@ -54,6 +55,7 @@ The changes are:
 - https://github.com/eclipse-syson/syson/issues/960[#960] [general-view] In the selection dialog of the creation tools for `Stakeholders` and `Actors`, display possible `Part Usage` candidates in a tree instead of a list.
 - https://github.com/eclipse-syson/syson/issues/1012[#1012] [general-view] Allow package nodes to be smaller than their default size
 - https://github.com/eclipse-syson/syson/issues/1006[#1006] [details] Display `FeatureValue.isDefault` and `FeatureValue.isInitial` in Core tab of `FeatureValue` concept.
+- https://github.com/eclipse-syson/syson/issues/1018[#1018] [libraries] Make customizing the default metamodels and libraries available in SysML projects easier by making default implementation `SysONDefaultLibrariesConfiguration` more extensible.
 
 
 === New features

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/configuration/SysMLEditingContextProcessor.java

@@ -36,7 +36,7 @@
 import org.springframework.stereotype.Service;
 
 /**
- * {@link IEditingContextProcessor} for SysML libraries. All SysML standard libraries should be loaded when a project
+ * {@link IEditingContextProcessor} for SysML libraries. All SysML default libraries should be loaded when a project
  * (i.e. an editing context) is loaded.
  *
  * @author arichard
@@ -46,12 +46,12 @@ public class SysMLEditingContextProcessor implements IEditingContextProcessor {
 
     private final Logger logger = LoggerFactory.getLogger(SysMLEditingContextProcessor.class);
 
-    private final SysMLStandardLibrariesConfiguration standardLibraries;
+    private final SysONDefaultLibrariesConfiguration defaultLibraries;
 
     private final IStudioCapableEditingContextPredicate studioCapableEditingContextPredicate;
 
-    public SysMLEditingContextProcessor(SysMLStandardLibrariesConfiguration standardLibraries, IStudioCapableEditingContextPredicate studioCapableEditingContextPredicate) {
-        this.standardLibraries = Objects.requireNonNull(standardLibraries);
+    public SysMLEditingContextProcessor(SysONDefaultLibrariesConfiguration standardLibraries, IStudioCapableEditingContextPredicate studioCapableEditingContextPredicate) {
+        this.defaultLibraries = Objects.requireNonNull(standardLibraries);
         this.studioCapableEditingContextPredicate = Objects.requireNonNull(studioCapableEditingContextPredicate);
     }
 
@@ -63,7 +63,7 @@ public void preProcess(IEditingContext editingContext) {
             siriusWebEditingContext.getDomain().getResourceSet().eAdapters().add(new SysONEContentAdapter());
 
             Instant start = Instant.now();
-            ResourceSet sourceResourceSet = this.standardLibraries.getLibrariesResourceSet();
+            ResourceSet sourceResourceSet = this.defaultLibraries.getLibrariesResourceSet();
             ResourceSet targetResourceSet = siriusWebEditingContext.getDomain().getResourceSet();
             /*
              * Use a common copier for all the resources to make sure cross-references are correctly copied.
@@ -93,7 +93,7 @@ public void preProcess(IEditingContext editingContext) {
             copier.copyReferences();
             Instant finish = Instant.now();
             long timeElapsed = Duration.between(start, finish).toMillis();
-            this.logger.info("Copy all standard libraries in the editing context in {} ms", timeElapsed);
+            this.logger.info("Copied all default libraries in the editing context in {} ms", timeElapsed);
         }
     }
 

backend/application/syson-application-configuration/src/main/java/org/eclipse/syson/application/configuration/SysMLStandardLibrariesConfiguration.java

@@ -0,0 +1,126 @@
+/*******************************************************************************
+ * Copyright (c) 2024, 2025 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.syson.application.configuration;
+
+import java.nio.file.Paths;
+import java.time.Duration;
+import java.time.Instant;
+import java.util.Collections;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.eclipse.emf.ecore.EPackage;
+import org.eclipse.emf.ecore.impl.EPackageRegistryImpl;
+import org.eclipse.emf.ecore.resource.ResourceSet;
+import org.eclipse.emf.ecore.resource.impl.ResourceSetImpl;
+import org.eclipse.sirius.components.emf.services.JSONResourceFactory;
+import org.eclipse.sirius.emfjson.resource.JsonResourceFactoryImpl;
+import org.eclipse.syson.application.libraries.SysONLibraryLoader;
+import org.eclipse.syson.application.libraries.SysONLibraryLoadingDefinition;
+import org.eclipse.syson.sysml.SysmlPackage;
+import org.eclipse.syson.sysml.helper.EMFUtils;
+import org.eclipse.syson.sysml.util.ElementUtil;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.context.annotation.Configuration;
+
+/**
+ * Configuration to load the KerML and SysML standard libraries.
+ *
+ * @author arichard
+ */
+@Configuration
+public class SysONDefaultLibrariesConfiguration {
+
+    public static final SysONLibraryLoadingDefinition KERML = new SysONLibraryLoadingDefinition(
+            "KerML Standard Library",
+            ElementUtil.KERML_LIBRARY_SCHEME,
+            Paths.get("kerml.libraries"),
+            Collections.singletonList(JsonResourceFactoryImpl.EXTENSION),
+            new JSONResourceFactory()::createResource);
+
+    public static final SysONLibraryLoadingDefinition SYSML = new SysONLibraryLoadingDefinition(
+            "SysML Standard Library",
+            ElementUtil.SYSML_LIBRARY_SCHEME,
+            Paths.get("sysml.libraries"),
+            Collections.singletonList(JsonResourceFactoryImpl.EXTENSION),
+            new JSONResourceFactory()::createResource);
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(SysONDefaultLibrariesConfiguration.class);
+
+    private ResourceSet librariesResourceSet;
+
+    public SysONDefaultLibrariesConfiguration() {
+    }
+
+    public ResourceSet getLibrariesResourceSet() {
+        if (this.librariesResourceSet == null) {
+            this.librariesResourceSet = this.createAndInitializeResourceSetWithLibraries();
+        }
+        return this.librariesResourceSet;
+    }
+
+    protected ResourceSet createAndInitializeResourceSetWithLibraries() {
+        Instant start = Instant.now();
+
+        final EPackage.Registry ePackageRegistry = new EPackageRegistryImpl();
+        final ResourceSet resourceSet = new ResourceSetImpl();
+        resourceSet.setPackageRegistry(ePackageRegistry);
+
+        this.populateWithDefaultEPackages(ePackageRegistry);
+        this.populateWithDefaultLibraries(resourceSet);
+
+        EMFUtils.resolveAllNonDerived(resourceSet);
+
+        Instant finish = Instant.now();
+        long timeElapsed = Duration.between(start, finish).toMillis();
+        LOGGER.info("Initialization of default libraries completed in %sms".formatted(timeElapsed));
+
+        return resourceSet;
+    }
+
+    /**
+     * Provides the default libraries. The default libraries are made available to all SysML projects of the
+     * application.
+     *
+     * Override this to customize the standard libraries or add extra default libraries to all SysML projects.
+     *
+     * @return a (non-{@code null}) {@link List} of (non-{@code null}) {@link SysONLibraryLoadingDefinition}.
+     */
+    protected List<SysONLibraryLoadingDefinition> getDefaultLibraries() {
+        return Stream.of(KERML, SYSML).toList();
+    }
+
+    /**
+     * Provides the default metamodels to register.
+     *
+     * @return a (non-{@code null}) {@link List} of (non-{@code null}) {@link EPackage}.
+     */
+    protected List<EPackage> getDefaultEPackages() {
+        return Collections.singletonList(SysmlPackage.eINSTANCE);
+    }
+
+    protected void populateWithDefaultLibraries(final ResourceSet resourceSet) {
+        final SysONLibraryLoader sysonLibraryLoader = new SysONLibraryLoader();
+        for (final SysONLibraryLoadingDefinition libraryLoadingDefinition : this.getDefaultLibraries()) {
+            sysonLibraryLoader.loadLibraryResources(resourceSet, libraryLoadingDefinition);
+        }
+    }
+
+    protected void populateWithDefaultEPackages(final EPackage.Registry ePackageRegistry) {
+        for (final EPackage ePackage : this.getDefaultEPackages()) {
+            ePackageRegistry.put(ePackage.getNsURI(), ePackage);
+            LOGGER.info("Registered EPackage '%s' (prefix '%s') against URI '%s'".formatted(ePackage.getName(), ePackage.getNsPrefix(), ePackage.getNsURI()));
+        }
+    }
+}