// Create the nested class.
TypeDeclaration classDeclaration = ast.newTypeDeclaration();
classDeclaration.setName(ast.newSimpleName(_getProxyName()));
String rollbackType = getClassName(Rollbackable.class, state, root);
classDeclaration.superInterfaceTypes().add(
ast.newSimpleType(createName(ast, rollbackType)));
// Add a commit method.
MethodDeclaration commit = ast.newMethodDeclaration();
commit.setName(ast.newSimpleName(_getCommitMethodName(false)));