Summary

Transitioning an issue via /rest/api/3/issue/ {issueid}/transitions clears data such as summary if these fields are not provided in the REST call.

Steps to Reproduce

1. Add a screen to a transition
2. Make a call to /rest/api/3/issue/ {issueid}/transitions to transition an issue with field updates like below:

   {
       "transition": {
           "id": 21
       },
       "fields": {
           "description": {
               "version": 1,
               "type": "doc",
               "content": [
                   {
                       "type": "paragraph",
                       "content": [
                           {
                               "type": "text",
                               "text": "this is my description now"
                           }
                       ]
                   }
               ]
           },
           "customfield_10054": "http://www.ramblingvapers.com",        
           "customfield_10051": {
               "version": 1,
               "type": "doc",
               "content": [
                   {
                       "type": "paragraph",
                       "content": [
                           {
                               "type": "text",
                               "text": "root cause"
                           }
                       ]
                   }
               ]
           },
           "customfield_10052": {
               "version": 1,
               "type": "doc",
               "content": [
                   {
                       "type": "paragraph",
                       "content": [
                           {
                               "type": "text",
                               "text": "some text"
                           }
                       ]
                   }
               ]
           },
           "customfield_10053": {
               "version": 1,
               "type": "doc",
               "content": [
                   {
                       "type": "paragraph",
                       "content": [
                           {
                               "type": "text",
                               "text": "texty text"
                           }
                       ]
                   }
               ]
           }        
       }
   }
   

3. Make a further call to transition again:

   {
       "transition": {
           "id": 11
       }
   }
   

Expected Results

The field values remain the same

Actual Results

The field values such as Description are cleared.

Workaround

Currently the best workaround is to use the API V2 endpoint: The Jira Cloud platform REST API V2: Transition Issue