So a barebones example of what I have you can see below. This is what the compiler is telling me:

error: incompatible types
        for (PluginSnapshot snapshot : this.platform.getPlugins()) {
                                                               ^
  required: PluginSnapshot
  found:    Object

This error makes no sense because the type is specified as PluginSnapshot. Any ideas why this could be happening? The issue can be recreated with the following code.

public class Main {
    public static void main(String... args) {
        Platform platform = null;
        for (PluginSnapshot plugin : platform.getPlugins()) {
            // ...
        }
    }
}

public interface Platform<P extends Player> {
    List<P> getPlayers();
    List<PluginSnapshot> getPlugins();
}

public interface Player {
    UUID getUniqueId();
}

public interface PluginSnapshot {
    String name();
}