private String textureName(Texture texture) {
        if (texture == null) {
            return null;
        }
        AssetKey key = texture.getKey();
        if (key != null) {
            return key.toString();
        } else {
            return null;
        }
    }
Add a texture for a specific map name at the location of another existing texture (on the master map).
@param texture A texture to add to the atlas.
@param mapName A freely chosen map name that can be later retrieved as a Texture.
@param sourceTextureName Name of the master map used for the location.
jme3-core/src/tools/java/jme3tools/optimize/TextureAtlas.java