Fix #945 Log level for rate-limited error logging (#946)

Author: seratch

slack-api-client/src/main/java/com/slack/api/methods/impl/AsyncRateLimitExecutor.java

@@ -188,7 +188,8 @@ private static <T extends SlackApiTextResponse> T handleIOException(String teamI
     private static void logSlackApiException(String teamId, String methodName, SlackApiException e) {
         if (e.getResponse().code() == 429) {
             String retryAfterSeconds = e.getResponse().header("Retry-After");
-            log.error("Got a rate-limited response from {} API (team: {}, error: {}, retry-after: {})",
+            // As long as you use this executor, the API client automatically retries the same request for you
+            log.warn("Got a rate-limited response from {} API (team: {}, error: {}, retry-after: {})",
                     methodName,
                     teamId,
                     e.getMessage(),