creates default entity tree

artemis/artemis-graph/src/main/java/org/eclipse/jnosql/artemis/graph/DefaultEntityTree.java

@@ -0,0 +1,52 @@
+/*
+ *  Copyright (c) 2019 Otávio Santana and others
+ *   All rights reserved. This program and the accompanying materials
+ *   are made available under the terms of the Eclipse Public License v1.0
+ *   and Apache License v2.0 which accompanies this distribution.
+ *   The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v10.html
+ *   and the Apache License v2.0 is available at http://www.opensource.org/licenses/apache2.0.php.
+ *
+ *   You may elect to redistribute this code under either of these licenses.
+ *
+ *   Contributors:
+ *
+ *   Otavio Santana
+ */
+package org.eclipse.jnosql.artemis.graph;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * The default implementation of {@link EntityTree}
+ */
+final class DefaultEntityTree implements EntityTree {
+
+    private final Object data;
+
+    private final List<EntityTree> children = new ArrayList<>();
+
+    DefaultEntityTree(Object data) {
+        this.data = data;
+    }
+
+    void add(EntityTree tree) {
+        this.children.add(tree);
+    }
+
+    @Override
+    public <T> T getData() {
+        return (T) data;
+    }
+
+    @Override
+    public List<EntityTree> getChildren() {
+        return Collections.unmodifiableList(children);
+    }
+
+    @Override
+    public boolean isLeaf() {
+        return children.isEmpty();
+    }
+}