SLING-8028 Split FeatureExtensionHandler into MergeHandler and PostPr…

…ocessor

Provide ArtifactProvider interface to enable extension handlers to
resolve artifacts.

src/main/java/org/apache/sling/feature/builder/ArtifactProvider.java

@@ -0,0 +1,31 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.apache.sling.feature.builder;
+
+import java.io.File;
+
+import org.apache.sling.feature.ArtifactId;
+
+public interface ArtifactProvider {
+
+    /**
+     * Provide the artifact with the given id.
+     * @param id The artifact id
+     * @return The file or {@code null}
+     */
+    File provide(ArtifactId id);
+}