When we get a page value from vertex/edge API like this

GET xxx/graphs/hugegraph/graph/vertices?page&limit=3

We will get page = xxxxx to scan next page's values. however, when we get page value containis +, like this:
ab4c+def123

The url decoder(@QueryParam) will auto encode it to a space(refer to W3C-HTML4.01's request), which leads to some error. So we condiser to 3 ways to solve it:

1. replace all + to %2B before return page to users (refer to W3C hex code)
2. when param contains +, server will get a space, then we replace all space to +
3. use getQueryString() from HTTPRequest's URI, then split it and handle params.