// before May 1st, 2011
pair("metadataParams", toMap(pair("mapVersion", "v1"))),
pair("sphericalMercator",
true)));
Layer merc = new WMS("World Map",
"http://maps.opengeo.org/geowebcache/service/wms", toMap(pair(
"layers", "bluemarble")), toMap(pair("opacity", 0.4),
pair("isBaseLayer", false), pair("wrapDateLine", true)));
// create a vector layer for drawing