SystemPromptTemplate removes double curly braces {{ }} when rendering prompts

[SaurabhDesaiCeloxis]

Description

When using SystemPromptTemplate in Spring AI, any usage of double curly braces like {{ this is my line }} gets removed entirely in the final output, instead of escaping to { this is my line } or remaining as-is.

Sample code

String template = "{{ this is my line }}";
SystemPromptTemplate promptTemplate = new SystemPromptTemplate(template);
String result = promptTemplate.create(Map.of()).getContents();
System.out.println(result); 

Expected output

{ this is my line }

Actual output

this is my line

Is there anything I am doing wrong here, or can anyone explain why this is happening?

[sunyuhan1998]

Hi @SaurabhDesaiCeloxis, I replied to you in the issue with the same question: #3721 (comment)