Fixes #3593 - Zendesk import creates new ticket numbers rather than using the Zendesk ticket IDs also as ticket numbers in Zammad.

lib/sequencer/unit/import/zendesk/ticket/mapping.rb

@@ -17,6 +17,7 @@ class Sequencer
               provide_mapped do
                 {
                   id:                       resource.id,
+                  number:                   resource.id,
                   title:                    subject,
                   owner_id:                 owner_id,
                   group_id:                 group_id,

test/integration/zendesk_import_test.rb

@@ -329,6 +329,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
       {
         id:   2,
         data: {
+          number:                   '2',
           title:                    'test',
           note:                     nil,
           create_article_type_id:   1,
@@ -350,6 +351,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
       {
         id:   3,
         data: {
+          number:                   '3',
           title:                    'Bob Smith, here is the test ticket you requested',
           note:                     nil,
           create_article_type_id:   10,
@@ -371,6 +373,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
       {
         id:   5,
         data: {
+          number:                   '5',
           title:                    'Twitter',
           note:                     nil,
           create_article_type_id:   6,
@@ -387,6 +390,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
       {
         id:   143,
         data: {
+          number:                   '143',
           title:                    'Basti ist cool',
           note:                     nil,
           create_article_type_id:   8,
@@ -403,6 +407,7 @@ class ZendeskImportTest < ActiveSupport::TestCase
       {
         id:   145,
         data: {
+          number:                   '145',
           title:                    'closed ticket - should be archived and imported',
           note:                     nil,
           create_article_type_id:   11,