public void setYamlOverrideValue(final OverrideValue<String> yamlOverride) {
        if (yamlOverride == null) {
            this.yamlOverrideValue = OverrideValue.unSet(String.class);
        } else if (yamlOverride.isHasOverride()) {
            setYamlOverrideValue(yamlOverride.getValueAsOptional().orElse(null));
        } else {
            this.yamlOverrideValue = yamlOverride;
        }
    }
Remove any override value at the yaml level, whether null or non-null
stroom-core-shared/src/main/java/stroom/config/global/shared/ConfigProperty.java