WildFly follows: LGPL 2.1 License
All dependencies of this project are available under the LGPL or a compatible license.
To know more about this "LGPL" please refer to: GNU Lesser General Public License - Wikipedia, the free encyclopedia
In general: "The license allows developers and companies to use and integrate software released under the LGPL into their own (even proprietary) software without being required by the terms of a strong copyleft license to release the source code of their own components. The license only requires software under the LGPL be modifiable by end users via source code availability"
The LGPL wording would be confusing for a lot of lawyers. I am only deploying a .war file so no code would be distributed. I would assume any use of WildFly libraries in that case would considered dynamically linked? I'm guessing I would need to talk to RedHat sales to make sure.
For WildFly, you do not need to sign anything, you can use it freely.