public static <A> A alias(Class<A> cl, Expression<? extends A> expr) {
        return aliasFactory.createAliasForExpr(cl, expr);
    }
Create a new alias proxy of the given type for the given expression

@param cl type of the alias
@param expr underlying expression
@return alias instance
querydsl-core/src/main/java/com/querydsl/core/alias/Alias.java