Fallback doesn't work as expected

[Jezza]

For example:

first.toml

[metadata.a]
name = "value"

[metadata.b]
name = "value"

second.toml

[metadata.b]
name = "value"

[metadata.c]
name = "value"

If I load first.toml, set the result of that to the defaults for second.toml.

Toml defaults = new Toml().read("first.toml");
Toml custom = new Toml(defaults).read("second.toml");

I'd expect to be able to access second.toml's version of metadata.b and metadata.c, but first's version of metadata.c.
But right now, it overrides first.toml's declarations, so I can't access metadata.a.

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It would also be nice if it could get to a point where something like this works:

first.toml

[metadata.a]
name = "value"
values = [ "value0", "value1" ]

[metadata.b]
name = "value"

second.toml

[metadata.a]
values = [ "value0"]

When accessing metadata.a, you'd get second.toml's version of values, but inherit the rest from first.toml.