Parameters of inherited implementations not checked for compatibility with methods they implement

import java.util.function.Consumer;
import java.util.function.Supplier;
import org.checkerframework.checker.nullness.qual.Nullable;

abstract class StringSupplier implements Supplier<String> {
  private String s = "";

  public void accept(String s) {
    this.s = s;
  }

  @Override
  public String get() {
    return s;
  }
}

class Holder extends StringSupplier implements Consumer<@Nullable String> {}

class Foo {
  public static void main(String[] args) {
    Holder h = new Holder();
    ((Consumer<@Nullable String>) h).accept(null);
    h.get().hashCode();
  }
}

$ checker/bin/javac -processor org.checkerframework.checker.nullness.NullnessChecker Foo.java && java Foo
Exception in thread "main" java.lang.NullPointerException
  at Foo.main(Foo.java:24)

I started down this path because I noticed that it was possible to make the same type implement, e.g., both Consumer<String> and Consumer<@Nullable String>. However, I wasn't finding a way to turn that into a NullPointerException (except by using a lambda, as in #2723). When I finally found the NullPointerException above, it turned out that I didn't need to implement Consumer twice to trigger it. (It does still seem a little dicey that it's possible to have a type that implements both Consumer<String> and Consumer<@Nullable String> (since Java doesn't allow implementing, say, Consumer<String> and Consumer<Object>), but that's the worst I can say about that at the moment.)

Source file and -version -verbose -AprintAllQualifiers output attached.