Corrected with rubocop cop 'Style/MultilineOperationIndentation'.

.rubocop.yml

@@ -268,8 +268,6 @@ Lint/AmbiguousRegexpLiteral:
   Enabled: false
 Rails/Validation:
   Enabled: false
-Style/MultilineOperationIndentation:
-  Enabled: false
 Lint/Eval:
   Enabled: false
 Style/ModuleFunction:

app/models/history.rb

@@ -163,7 +163,7 @@ returns
         history_object_related.id,
         requested_object_id,
       )
-      .order('created_at ASC, id ASC')
+      .order('created_at ASC, id ASC') # rubocop:disable Style/MultilineOperationIndentation
     end
     asset_list = {}
     list = []

app/models/online_notification.rb

@@ -116,8 +116,8 @@ return all online notifications of an object
       object_lookup_id: object_id,
       o_id: o_id,
     )
-    .order( 'created_at DESC, id DESC' )
-    .limit( 10_000 )
+    .order( 'created_at DESC, id DESC' ) # rubocop:disable Style/MultilineOperationIndentation
+    .limit( 10_000 ) # rubocop:disable Style/MultilineOperationIndentation
 
     list = []
     notifications.each do |item|

lib/core_ext/string.rb

@@ -46,7 +46,7 @@ class String
       end
       c
     }
-    .join('')
+    .join('') # rubocop:disable Style/MultilineOperationIndentation
   end
 
 =begin

lib/import/otrs2.rb

@@ -1262,7 +1262,7 @@ module Import::OTRS2
     if !user
       begin
         display_name = Mail::Address.new( article['from'] ).display_name ||
-          ( Mail::Address.new( article['from'] ).comments && Mail::Address.new( article['from'] ).comments[0] )
+                       ( Mail::Address.new( article['from'] ).comments && Mail::Address.new( article['from'] ).comments[0] )
       rescue
         display_name = article['from']
       end