added nonnull assertions

build.gradle

@@ -28,6 +28,7 @@ dependencies {
 
 	// PSA: Some older mods, compiled on Loom 0.2.1, might have outdated Maven POMs.
 	// You may need to force-disable transitiveness on them.
+	compileOnly "com.google.code.findbugs:jsr305:${project.jsr305_version}"
 }
 
 processResources {