@Override
    public int hashCode() {
        int result = super.hashCode();
        result = 31 * result + (fieldValue != null ? fieldValue.hashCode() : 0);
        result = 31 * result + (expression != null ? expression.hashCode() : 0);
        result = 31 * result + (createMissingPath ? 1 : 0);
        result = 31 * result + (removeIfZero ? 1 : 0);
        return result;
    }
@return Returns true if this assignment is an arithmetic operation.
document/src/main/java/com/yahoo/document/fieldpathupdate/AssignFieldPathUpdate.java