code: private ZooClassDef locateClassDefinition(Class<?> cls, Node node) {
  		ZooClassDef def = cache.getSchema(cls, node);
  		if (def == null || def.jdoZooIsDeleted()) {
  			return null;
  		}
  		return def;
  	}
docs: Checks class and disk for class definition.
  @param cls
  @param node
  @return Class definition, may return null if no definition is found.