Fix style issue

Author: Samiul-TheSoccerFan

server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java

@@ -399,7 +399,9 @@ protected static void parseProperties(Builder objBuilder, Map<String, Object> pr
                         throw new MapperParsingException(
                             "The mapper type ["
                                 + type
-                                + "] does not exist. It might have been created within a future version or requires a plugin to be installed. Check the documentation."
+                                + "] does not exist."
+                                + " It might have been created within a future version or requires a plugin to be installed."
+                                + " Check the documentation."
                         );
                     }
                     Mapper.Builder fieldBuilder;