External system import (Csv/Json) does not write change history when clearing a custom field

Issue Summary

When clearing the value of a custom filed via External System Import function.
The value of a custom field can be removed, but this operation is not shown in change history.

• It seems a bug since the change history is written when clearing up the value of custom field via UI.
• Either Csv or Json import do not work

Steps to Reproduce

1. A custom filed has value, and be ready to clear
2. Sample Json to clear up the value of a custom field.

   {
   	"projects": [
   		{
   			"name": "Scrum Two",
   			"key": "ST",
   			"description": "This is a sample data",
   			"issues": [
   				{
   					"key" : "ST-7",
   					"updated" : "P-1D",
   					"summary" : "My test",
   					"labels" : [ "ari" ],
   		            "customFieldValues": [
   		                {
   		                    "fieldName": "customfield_10602",
   		                    "fieldType": "com.atlassian.jira.plugin.system.customfieldtypes:textfield",
   		                    "value": ""
   		                }
   		            ]
   				}
   			]
   		}
   	]
   

    

It can be reproduced by CSV as well.

issue-key,summary,test_field
"ST-7","Ny chore3","<<!clear!>>"

Expected Results

The change history should be written, since it is written when removing the value of custom field from UI.

Actual Results

The change history is not written.

Workaround

Currently there is no known workaround for this behavior.