add class attribute to validator

Signed-off-by: Stefan Niederhauser <[email protected]>

Author: nidi3

graphviz-java/src/main/java/guru/nidi/graphviz/attribute/validate/AttributeConfigs.java

@@ -48,6 +48,7 @@ static List<AttributeConfig> get(String name) {
         add("bgcolor", entry("GC", asList(COLOR, COLOR_LIST)));
         add("center", entry("G", BOOL, false));
         add("charset", entry("G", STRING, "UTF-8"));
+        add("class", entry("ENGC", STRING));
         add("clusterrank", entry("G", CLUSTER_MODE, "local").engines(DOT));
         add("color", entry("ENC", asList(COLOR, COLOR_LIST), "black"));
         add("colorscheme", entry("ENCG", STRING, ""));