Returns.java

import org.checkerframework.checker.nullness.qual.*;

// The return of a lambda is a lambda

interface ConsumerSupplier {
    ConsumerR get();
}

interface ConsumerR {
    void method(@Nullable String s);
}

interface SupplierSupplier {
    SupplierRe get();
}

interface SupplierRe {
    @NonNull String method();
}

class MetaReturn {

    //:: error: (dereference.of.nullable)
    ConsumerSupplier t1 = () -> (s) -> s.toString();
    ConsumerSupplier t2 =
            () -> {
                return (String s) -> {
                    //:: error: (dereference.of.nullable)
                    s.toString();
                };
            };

    SupplierSupplier t3 =
            () -> {
                //:: error: (return.type.incompatible)
                return () -> null;
            };

    SupplierSupplier t4 =
            () -> {
                return ""::toString;
            };
}