[Fix] Fix processing of '\v' in libucl

Issue: #2045

contrib/libucl/ucl_emitter_utils.c

@@ -102,7 +102,9 @@ ucl_elt_string_write_json (const char *str, size_t size,
 	func->ucl_emitter_append_character ('"', 1, func->ud);
 
 	while (size) {
-		if (ucl_test_character (*p, UCL_CHARACTER_JSON_UNSAFE|UCL_CHARACTER_DENIED)) {
+		if (ucl_test_character (*p, (UCL_CHARACTER_JSON_UNSAFE|
+				UCL_CHARACTER_DENIED|
+				UCL_CHARACTER_WHITESPACE_UNSAFE))) {
 			if (len > 0) {
 				func->ucl_emitter_append_len (c, len, func->ud);
 			}
@@ -122,9 +124,15 @@ ucl_elt_string_write_json (const char *str, size_t size,
 			case '\f':
 				func->ucl_emitter_append_len ("\\f", 2, func->ud);
 				break;
+			case '\v':
+				func->ucl_emitter_append_len ("\\v", 2, func->ud);
+				break;
 			case '\\':
 				func->ucl_emitter_append_len ("\\\\", 2, func->ud);
 				break;
+			case ' ':
+				func->ucl_emitter_append_character (' ', 1, func->ud);
+				break;
 			case '"':
 				func->ucl_emitter_append_len ("\\\"", 2, func->ud);
 				break;