parsers.put(type, build(converter, type));
    }

    private <T> void registerStringConverter(NotationConverter<String, T> converter, Class<T> type) {
        parsers.put(type, build(new CharSequenceNotationConverter<Object, T>(converter), type));
    }

    private void registerConverters() {
        registerConverter(new DoubleNumberConverter(Double.class), Double.class);

Class <org.gradle.internal.typeconversion.CharSequenceNotationConverter> is not annotated (directly or via its package) with @org.gradle.api.NonNullApi in (CharSequenceNotationConverter.java:0)