Fields specified in Existing Contact:"Fields to lock" are not stored

Problem/Motivation

Fields specified in Existing Contact "Fields to lock" are not stored, either in the Webform results or in the CiviCRM Contact record, in the following conditions:

• New Contact: If "Don't lock fields that are empty" is unchecked.
• Existing contact: Always.

Proposed resolution

In file webform_civicrm/includes/wf_crm_webform_postprocess.inc.wf_crm_webform_postprocess:

• isFieldHiddenByExistingContactSettings. Indicates if the field is designated as a "Fields to lock" to be hidden (optionally if not blank) for existing contacts. It also returns true (I presume incorrectly) in the case of a new contact if "Don't lock fields that are empty" is unchecked.
• fillDataFromSubmission: If for any submitted value the above function returns true, then that value is removed from the Webform submission.

I think there are two issues here:

1. isFieldHiddenByExistingContactSettings incorrectly returns true on new contacts if "Don't lock fields that are empty" is unchecked, even though no field is actually locked/hidden on the submitted form.
2. It is not clear why fillDataFromSubmission nulls any data fields that are hidden (or potentially hidden), writing nulls into the webform results. If the hidden/locked fields were populated from the Civi database and are unchangeable in the form, they should be treated as valid submitted fields, written into the Webform results and harmlessly re-written to the contact record.

In any case, all submitted form field values (hidden, locked or otherwise) should be made available in the Webform results and Civi contact record.

Remaining tasks

(reviews needed, tests to be written or run, documentation to be written, etc.)

User interface changes

(New or changed features/functionality in the user interface, modules added or removed, changes to URL paths, changes to user interface text.)

API changes

(API changes/additions that would affect module, install profile, and theme developers, including examples of before/after code if appropriate.)

Data model changes

(Database or configuration data changes that would make stored data on an existing site incompatible with the site's updated codebase, including changes to hook_schema(), configuration schema or keys, or the expected format of stored data, etc.)

Original report by [username]

(Text of the original report, for legacy issues whose initial post was not the issue summary. Use rarely.)