Modifying a value inside the config file

[drori200]

Currently i know how to get a value from the config file using the class. This is all fine but there's the problem of no clear way to edit the values of the config files. Even with the ConfigHolder way there is no straight way to set a new value.

[Gmugra]

To be honest, the library is based on the assumption that the application does not need to modify the configuration(s).
I.e. the typical scenario is that we find/load configuration(s) at the start and that's it.

We get a specific configuration value as a result of combining (fallback/merging) different sources (including depending, for example, on environment variables). So, the application simply does not know where in the sources this value was.

For example, here is an example from the documentation:

MyConfig myConfig =
    ConfigFactory.builder()
        .setLoadStrategy(LoadStrategy.MERGE)
        .addSource("file:~/myconfig.xml")
        .addSource("classpath:config/myconfig-owner.xml")
        .addSource("jar:file:path/to/some.jar!/path/to/myconfig.properties")
        .addSource("https://somewhere.com/myconfig.toml")
        .addSource("file:./myconfig.json")
        .addSource("file:./myconfig.yaml")
        .build()
        .create(MyConfig.class);

Here we have 6 merged sources, and MyConfig instance just does not know where the particular value in a particular case came from.

Thus, the wish to save the changed configuration somewhere faces the problem: where?
In which of the many sources should the change be saved?
Especially considering that the source may be read-only. (E.g. environment variable cannot be modified from Java application, but can be read and can be configuration source -> loader system:env)

Thus, the back-synchronization of the changed configuration values is not a simple problem, which the library does not solve in any way for the moment.

Exists plan to add kind of such feature: #305
But, to tell the truth, i still not 100% sure is this feature has real value or not: low priority at the moment.