Json converts & in a String to \u0026

I am trying to extract text from pdf and write it into a json file. While extracting unicode characters the Json converts all & to \u0026. For example my actual String is &#1588. (which represents ش). It prints correctly to a .txt file, to console etc. But when I try to print this string to a Json file it shows \u0026#1588;.

I am using Java, and the code is

Gson gson = new Gson();
String json = gson.toJson(pdfDoc);

Note: pdfDoc is an object, that contains all the details (position, color, font.. etc) of characters inside the input PDF document. I am using gson-2.2.1.jar.