Compile error "cannot find symbol P"

After upgrading stuff the following line

https://github.com/itinance/react-native-fs/blob/fcb62f622969be4634a8e2aebc67235bd1075c78/android/src/main/java/com/rnfs/RNFSManager.java#L119

throws the following error

```
.../node_modules/react-native-fs/android/src/main/java/com/rnfs/RNFSManager.java:119: error: cannot find symbol
return android.os.Build.VERSION.SDK_INT <= android.os.Build.VERSION_CODES.P ? "w" : "rwt";
^
symbol: variable P
location: class VERSION_CODES
```

and can't figure out why. Previously `2.18.0` was compiling fine. Now it happens also with `2.19.0`.