A good event system for your project.

Gradle

repositories {
    maven {
        name = "ferra13671-maven"
        url = "https://ferra13671.github.io/maven/"
    }
}

dependencies {
    implementation "com.ferra13671:mega-events:latest" //Replace 'latest' with the version of MegaEvents you need.
}

Example

For example check out example/src/main/java/example/Main.java.