NoSuchFieldError: leafDecayBlacklist
I have read your post about how to add ModloaderMP. I am adding ver. 4.2 of ModloaderMP to your latest server jar file and I receive the error as in the log file in the attached zip file : NoSuchFieldError: leafDecayBlacklist. Also included in the zip is your server jar with ModloaderMP added and nothing else. This is the jar I used when the error occurred. I went back to your server 1.1.6 jar with the same result. All I am adding is ModloaderMP nothing else without copying across the two files you say not to in your post and then I change the ModloaderMP setting to true in the 'poseidon.yml'. I tried adding Forge at one point as well as ModloaderMP and a different crash message, still, without ModloaderMP there was no point in pursuing Forge any further.
https://www.mediafire.com/file/dkeftsjmge9w5q2/bukkit1060-project-posiden-1.1.7.zip/file
Poseidon has had so many internal changes ModloaderMP support might be actually dropped.
There is still a page that advertises ModloaderMP and how to install it so I am still hopeful it might be something that they intend to support, I'll keep my fingers crossed until I hear otherwise.
Currently, ModLoaderMP isn't supported on the newest version. I believe 1.0.9 was the last Poseidon version to support it, but I might be wrong. I plan to fix support for ModLoaderMP, however, it is low on my list currently.