unable to do URLEncode while invoking Google Translator REST service from Siebel BS

We have a requirement to call google translator REST Api for translating "Japanese to English". We have been using below service since 2013:

https://www.googleapis.com/language/translate/v2?source=ja&model=nmt&q=JAPANESE TEXT&target=en&key=UNIQUE_KEY

We have a custom webservice which invokes above REST service by substituting Japanese text to the "q" and unique authentication key to "key" parameters in above header, by using the BS "EAI HTTP Transport" and "SendReceive" method. It was working fine till this Jan 2017.

But it started returning junk values now, after doing detailed analysis I found that, it's an Unicode/encoding issue. While passing Japanese characters in URL from siebel to Google, Japanese characters are encoded with different values which google can't understand. Other programming languages uses "urlencode" function to encode this Japanese characters before adding it in URL. Siebel don't have any functions other than escape for this purpose.