Unlike synthetic accessor methods, these synthetic covariant methods are hard or impossible to kill. Generics anyone?

GenericCovariants.java

interface Thing<T> {
  T thing();
}

class CharSequenceThing implements Thing<CharSequence> {
  @Override public CharSequence thing() {
    return "CharSequence!";
  }
}

output.txt

$ javap -p Thing CharSequenceThing

Compiled from "GenericCovariants.java"
interface Thing<T> {
  public abstract T thing();
}

Compiled from "GenericCovariants.java"
class CharSequenceThing implements Thing<java.lang.CharSequence> {
  CharSequenceThing();
  public java.lang.CharSequence thing();
  public java.lang.Object thing();
}