How does --warnings_allowlist_file works? I tried many ways but no luck

[bamtang-dev]

Hello, I'm trying to use --warnings_allowlist_file to dismiss this warning type:

warning JSC_UNRECOGNIZED_TYPE_ERROR: Bad type annotation. Unknown type XYZ

I know it is reading my file because if it doesn't find the file the compiler just crash with:

java.lang.RuntimeException: java.io.FileNotFoundException: pallowlist.txt (The system cannot find the file specified)

Is the path absolute, relative?, what is the format of the line? I feel my warning is not correct or not accepted, but no error is shown