Unable to make connection call using smarAPi.generateSession

[Narendra swami]

User user = smartApi.generateSession(lRDto.getClientcode(), lRDto.getPassword(), lRDto.getTotp());

		return ResponseEntity.status(HttpStatus.ACCEPTED).body(user.toString());

exception createPostRequest
Parameter specified as non-null is null: method okhttp3.Request$Builder.header, parameter value
Parameter specified as non-null is null: method okhttp3.OkHttpClient.newCall, parameter request