Inference failure calling unmarked method

[jeffrey-easyesi]

With NullAway:WarnOnGenericInferenceFailure enabled, this code now gets a warning:

import org.jspecify.annotations.*;

@NullUnmarked
class StringUtils {
    static <T extends CharSequence> T defaultIfEmpty(T str, T defaultStr) {
        return str == null || str.isEmpty() ? defaultStr : str;
    }
}

@NullMarked
class Test {
    static String f(@Nullable String s) {
        return StringUtils.defaultIfEmpty(s, ""); // inference failure: type variable T constrained to be both @NonNull and @Nullable
    }
}

I think this is a false positive: defaultIfEmpty's parameter and return types are unspecified-nullness and shouldn't be constraining T.
(Either .<String>defaultIfEmpty or .<@Nullable String>defaultIfEmpty is allowed with no error.)

[msridhar]

Thanks for the report! I'll try to dig in soon. We don't fully model unspecified nullness, and this might be a consequence of that.