How to escape ```\n``` char which is not at the end of the line of the string using java?

I have a csv string. A sample would be ->

String str = "Name, Age, Gender, Description\n"
           + "Test1, 12, M, Hello World\n"
           + "Test2, 21, M, Bye\nWorld";

When I open this in a csv viewer, Bye\nWorld is creating an issue. How do I escape the \n char in Bye\nWorld but not the ones that are at the end of each data using java? The logic should not detect the \n char at the end of each line, it should only detect the ones that are in the data. An example of the output I want is

Name, Age, Gender, Description
Test1, 12, M, Hello World
Test2, 21, M, Bye\\nWorld

This output will create a correct csv for this data.