From the docs:
To read the body content from a file, place the file under the __files directory. By default this is expected to be under src/test/resources when running from the JUnit rule. When running standalone it will be under the current directory in which the server was started. To make your stub use the file, simply call bodyFile() on the response builder with the file’s path relative to __files:
Is it possible to change it? Why would WireMock insist on this specific directory?