Add check for existing key to MessagesCacheInsertSharedMultiRecipientPayloadAndViewsScript

service/src/main/resources/lua/insert_shared_multirecipient_message_data.lua

@@ -4,6 +4,10 @@ local sharedMrmKey = KEYS[1] -- [string] the key containing the shared MRM data
 local mrmData      = ARGV[1] -- [bytes] the serialized multi-recipient message data
 -- the remainder of ARGV is list of recipient keys and view data
 
+if 1 == redis.call("EXISTS", sharedMrmKey) then
+    return redis.error_reply("ERR key exists")
+end
+
 redis.call("HSET", sharedMrmKey, "data", mrmData);
 redis.call("EXPIRE", sharedMrmKey, 604800) -- 7 days