@Override
    public Void visit(SubQueryExpression<?> query, Void context) {
        append("(");
        serialize(query.getMetadata(), false, true);
        append(")");
        return null;
    }
{@code JDOQLSerializer} serializes Querydsl queries and expressions into JDOQL strings

@author tiwe
querydsl-jdo/src/main/java/com/querydsl/jdo/JDOQLSerializer.java