If you are using OpenJDK, you need not worry about paying Oracle. I had a look at Everest and looks like you are using JavaFX which is bundled by default with Oracle JDK and not included in OpenJDK 8. You can include OpenJFX through Maven.
Also, have a look at how IntelliJ Community does their bundling. They are also JavaFX based and open source.
Disclaimer: I am not a lawyer, so take advice with a grain of salt.
If you are using OpenJDK, you need not worry about paying Oracle. I had a look at Everest and looks like you are using JavaFX which is bundled by default with Oracle JDK and not included in OpenJDK 8. You can include OpenJFX through Maven.
Also, have a look at how IntelliJ Community does their bundling. They are also JavaFX based and open source.
Disclaimer: I am not a lawyer, so take advice with a grain of salt.
Thank you! This was really helpful.