There is a problem with org.apache.struts2.json.JSONValidationInterceptor
This class is using StringEscapeUtils.escapeEcmaScript(String) to escape the generated JSON string.
The problem is that StringEscapeUtils.escapeEcmaScript escapes the apostrophes. Some JSON implementations accept the escaped apostrophes but some other don't and they are not able to parse the JSON.
I think there should be at least an option to disable apostrophe escaping. But as I believe escaping apostrophe is not part of the JSON specifications, the best would be to not allow apostrophe escaping.
As an example, here is a JSON string generated by the JSON plugin :
If you test it on http://jsonlint.com/, it says the syntax is incorrect.
See the original question on the Struts User ML