fix import

jme3-core/src/com/jme3/gde/core/sceneexplorer/nodes/animation/JmeAnimComposerChildren.java

@@ -37,6 +37,7 @@ import com.jme3.anim.AnimLayer;
 import com.jme3.gde.core.scene.SceneApplication;
 import java.util.ArrayList;
 import java.util.Collections;
+import java.util.Comparator;
 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.List;