@JsonIgnore
    public void setYamlOverrideValue(final String yamlOverrideValue) {

        // We cannot distinguish between a value that has been set in the yaml as say 10
        // and a default value of 10, so if the default matches the yaml then we treat the
        // yaml as unset.
        if (Objects.equals(defaultValue, yamlOverrideValue)) {
            // matches default so remove the yaml value
            this.yamlOverrideValue = OverrideValue.unSet(String.class);
        } else {
            this.yamlOverrideValue = OverrideValue.with(yamlOverrideValue);
        }
    }
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