JSON / REST special character problems: a solution

use base64 encoding and decoding to get around it

• in the REST message (outbound request): 

var wnotes_base64Encode=GlideStringUtil.base64Encode(worknote);

...

r.setStringParameter('u_work_notes', wn_base64encoded);

• in the counterpart REST endpoint code (ServiceNow example) (incoming): 

                 

var sdesc_base64Decoded=GlideStringUtil.base64Decode(wnotes_base64Encode);