Can't update record in odoo table

Question

I'm trying to update a record in odoo table. I first get field mapping of the table

customersFieldList = (Map<String, Map<String, Object>>)models.execute("execute_kw", asList(
                db, uid, password,
                "nbp.contracts", "fields_get",
                emptyList(),
                new HashMap() {{
                    put("attributes", asList("string", "help", "type"));
                }}
        ));

After that i try to update "phone" field, that is present in the field list. Here's the field that i'm trying to update (that comes from the response of the API call)

...
phone={string=Phone, type=char},
...

But when i try to update the record

 models.execute("execute_kw", asList(
                db, uid, password,
                "nbp.contracts", "write",
                asList(
                        asList(i),
                        new HashMap() {{ put("phone", "3937612052"); }}
                )
        ));

I'll get TypeError: cannot marshal <class '_thread.lock'> objects

Any suggestion? Thanks