@SuppressWarnings("unchecked")//does not produce non-null instances of T
    public static <T> NullExpression<T> nullExpression() {
        return (NullExpression<T>) NullExpression.DEFAULT;
    }
Create a null expression for the specified type

@return null expression
querydsl-core/src/main/java/com/querydsl/core/types/dsl/Expressions.java