There's no "Java" folder under "Packages"

[thelastbirth]

default_new_file_syntax (String) This is the path, relative to the Sublime base directory to the language file you'd like to load as the default. Default value is "Packages/Java/Java.tmLanguage"

But there's no "Packages/Java/".

The reason I installed this plugin is so that when I run things like "curl https://google.com | subl" I can view it in plaintext versus the weirdly selected "Markdown GFM" format, which looks horrible.

But I don't see how this plugin can help.