Multimaps with non-parameterized key does not generate @SafeVarargs annotation, causes "Possible heap pollution from parameterized vararg type" warning #1479

import com.google.common.collect.Multimap;
import org.immutables.value.Value;

public interface ImmutableMultimapSafeVarargs {
    // Correct annotation
    //    @SafeVarargs @SuppressWarnings("varargs")
    //    public final Builder putVals(ImmutableMultimapTest.Val<String> key, String... values) {
    @Value.Immutable
    interface ParamKey {
        Multimap<Val<String>, String> vals();
    }

    // Missing annotation
    //    @CanIgnoreReturnValue
    //    public final Builder putVals(String key, ImmutableMultimapSafeVarargs.Val<String>... values) {
    // [WARNING] ...ImmutableParamVal.java:[156,41] Possible heap pollution from parameterized vararg type
    //           ...ImmutableMultimapSafeVarargs.Val<java.lang.String>
    // [INFO] 1 warning
    @Value.Immutable
    interface ParamVal {
        Multimap<String, Val<String>> vals();
    }

    // Correct annotation
    //    @SafeVarargs @SuppressWarnings("varargs")
    //    public final Builder putVals(ImmutableMultimapTest.Val<String> key, ImmutableMultimapTest.Val<String>... values) {
    @Value.Immutable
    interface ParamBoth {
        Multimap<Val<String>, Val<String>> vals();
    }

    class Val<T> {
        private final T val;

        public Val(final T val) {
            this.val = val;
        }

        T get() {
            return val;
        };
    }
}