Do not serialize default values

[apupier]

Please describe the feature that you want to propose

When a property is set to its default value, it should not be serialized otherwise it ends up with a very large file which is hard to read.

it happens after we modify one of the values to a non default value

For instance for log:

additional: it can be convenient to have a setting to allow keeping these values too.

[Delawen]

Closing as duplicate of #503