Invalid Freemarker code is generated in template editor when using embedded date fields

• Type: Bug
• Status: Closed
• Resolution: Fixed
• Affects Version/s: 7.0.X, 7.1.X, Master
• Fix Version/s: 7.1.10 DXP FP10, 7.1.10.2 SP2, 7.1.3 CE GA4, 7.1.X, Master
• Component/s: Dynamic Data Mapping, Dynamic Data Mapping > Template Editor
• Labels:
  • ee-ts
  • liferay-dxp-71-sp2
  • liferay-fixpack-dxp-10-7110
• Branch Version/s:
  7.1.x
• Backported to Branch:
  Committed
• Fix Priority: 3
• Git Pull Request: https://github.com/pavel-savinov/liferay-portal/pull/316

Reproduction steps

1. Start the latest master
2. Create a new site
3. Create a new structure "struct1" with a Date field embedded into another one, e.g.: add a Text field named "T1" and inside that a Date field named "D1"
4. Click "Manage Templates" on struct1 and "Add" to open the template editor
5. Click "D1" on the left side, and a code like this will be added to the editor:

   <#assign T1.D1_Data = getterUtil.getString(T1.D1.getData())>
   
   <#if validator.isNotNull(T1.D1_Data)>
   	<#assign T1.D1_DateObj = dateUtil.parseDate("yyyy-MM-dd", T1.D1_Data, locale)>
   
   	${dateUtil.getDate(T1.D1_DateObj, "dd MMM yyyy - HH:mm:ss", locale)}
   </#if>
   

6. Save the template
7. Go to Web Contents, create a new "struct1" web content, fill both fields
8. Preview the web content

Expected: the date value of the web content article is shown correctly
actual: an error is shown instead of the web content:

An error occurred while processing the template.
Syntax error in template "20115#20151#36778" in line 1, column 12:
Encountered ".", but was expecting one of:
    "="
    "+="
    "-="
    "*="
    "/="
    "%="
    "++"
    "--"
    "in"
    ">"
1<#assign T1.D1_Data = getterUtil.getString(T1.D1.getData())> 
2 
3<#if validator.isNotNull(T1.D1_Data)> 
4	<#assign T1.D1_DateObj = dateUtil.parseDate("yyyy-MM-dd", T1.D1_Data, locale)> 
5 
6	${dateUtil.getDate(T1.D1_DateObj, "dd MMM yyyy - HH:mm:ss", locale)} 
7</#if>

Reproduced on:
7.1.x : Commit: ee3cc2d128e09e039854f643acc4d3963069dfc0
Master: Commit: 304c1ae6a8bd439f952ae662954dfef1c58848b0

Note
The problem seems to be that the generated FTL code is wrong: "T1.D1_Data" is an invalid variable name in FTL. However, the variable names can contain special characters, when they are escaped with "\": "T1\.D1_Data"