Everything Forge is Open Source on GitHub, you can literally see what you're downloading there.
No there are no viruses or trojans in Forge, many virus detectors like to flag executable files made by people who haven't paid to be whitelisted by the anti-virus maker
This log indicates the server being killed by the watchdog because it took over a minute for a single tick.
Provide debug.log for more info.
Why do you have Optifine on a server?
Ok now I'm seeing anti-patterns
Get rid of ModBlock and ModItem, you shouldn't need them.
Never use @OnlyIn
There's no reason to list your items in a list initializer and then iterate the list
You're letting your blocks and items drive their own registration rather than just registering them
Delete the build folder... I have a feeling the issue is Gradle asking case-blind Windows if a mixed-case old version is identical to the all-lower new one